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Screening and diagnosis of type 2 diabetes with hba1c blood,causes of medication administration errors in hospitals articles,www.gc eschenried,gc essegem jette - PDF 2016

Jean-Marie Ekoe MD, CSPQ, PD Zubin Punthakee MD, MSc, FRCPC Thomas Ransom MD, MSc, FRCPC Ally P.H. In the absence of evidence for interventions to prevent or delay type 1 diabetes, screening for type 1 diabetes is not recommended. The clinical spectrum of diabetes ranges from a low-risk to a higher-risk individual or to the symptomatic patient who needs immediate treatment. In contrast to other diseases, there is no distinction between screening and diagnostic testing. Type 1 diabetes mellitus is primarily a result of pancreatic beta cell destruction due to an immune-mediated process that is likely incited by environmental factors in genetically predisposed individuals. Although the relatively low prevalence of diabetes in the general population makes it unlikely that mass screening will be cost effective, testing for diabetes in people with risk factors for type 2 diabetes or with diabetes-associated conditions is likely to result in more benefit than harm and will lead to overall cost savings (12–17) .
A number of risk scores based on clinical characteristics have been developed to identify individuals at high risk of having undiagnosed diabetes. All individuals should be evaluated annually for type 2 diabetes risk on the basis of demographic and clinical criteria [Grade D, Consensus]. Definition, Classification and Diagnosis of Diabetes, Prediabetes and Metabolic Syndrome, p. Preconception care for women with pregestational diabetes is associated with better outcomes (10,11).
Women with pre-existing vascular complications are more likely to have poor pregnancy outcomes, and there may be progression in the degree of vascular damage (7). Women with type 1 (22,23) and type 2 diabetes (24) should have ophthalmological assessments before conception, during the first trimester, as needed during pregnancy and within the first year postpartum (25,26).
The incidence of hypertension complicating pregnancy is 40% to 45% in women with type 1 and type 2 diabetes (29).
There is conflicting information on whether first-trimester exposure to angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) is associated with an increased risk of congential malformations. Although rare, cardiovascular disease (CVD) can occur in women of reproductive age with diabetes.
Care by an interdisciplinary diabetes healthcare (DHC) team composed of diabetes nurse educators, dietitians, obstetricians and diabetologists both prior to conception and during pregnancy, has been shown to minimize maternal and fetal risks in women with diabetes (53–56).
An important first step in achieving good glycemic control is to set target glucose levels (2,54).
The limiting factor when seeking euglycemia in women with pregestational diabetes is the increased risk of hypoglycemia during pregnancy, particularly in the first trimester (60–64).
Frequent self-monitoring of blood glucose (SMBG) in pregnant women with type 1 diabetes is essential during pregnancy in order to obtain the level of glycemic control associated with better outcomes (57). Insulin Insulin therapy must be individualized and regularly adapted to the changing needs of pregnancy (82–85). CSII While use of CSII may be preferred by some women with type 1 diabetes, studies have not demonstrated superiority over basal-bolus regimen (89,96–99), and, in some studies, there have been more adverse outcomes with CSII (89,99).
Oral antihyperglycemic agents and type 2 diabetes A meta-analysis of first-trimester use of either glyburide or metformin and 1 meta-analysis of metformin alone did not show an increased incidence of congenital anomalies (100,101). Metformin and polycystic ovary syndrome Considerable research has been done on the use of metformin in women with polycystic ovary syndrome (PCOS) around the time of conception and during pregnancy.
In summary, higher-level evidence has not shown metformin to be of benefit in women with PCOS in pregnancy. In order to justify mass screening for a medical disorder, a set of criteria needs to be met (Table 1). There should be an accepted treatment or useful intervention for patients with the disease.
Treatment started at an early stage should be of more benefit than treatment started later. The cost should be economically balanced in relation to possible expenditure on medical care as a whole. Up until the publication of the 2 large-scale RCTs, the benefit of treatment of varying degrees of hyperglycemia in pregnancy was unclear (119,120). The HAPO study, published in 2008, was a prospective observational study designed to determine if hyperglycemia during pregnancy was associated with an increased risk of maternal or fetal complications, and whether a diagnostic threshold value based on adverse perinatal outcomes could be calculated (4). Obviously, adopting these recommendations in Canada will profoundly impact the healthcare system, healthcare providers and our pregnant patients. Assuming universal screening, the method of screening can be either a sequential or a 1-step process. The most common glucose test used in sequential screening is the 50 g GCT performed between 24 to 28 weeks of gestation, and it is the screening test recommended by the CDA in the 2008 guidelines.
The best data regarding the GCT as a screening test come from the Toronto Tri-Hospital study.
An additional question is whether there is a GCT threshold above which GDM can be reliably diagnosed. Those who subscribe to the notion that all cases of hyperglycemia in pregnancy need to be diagnosed and treated (i.e. Given this lack of evidence, it is possible that the decision regarding the recommended screening method will be determined by the economic implications on the healthcare resources.
There are no economic analyses of the impact of the newly proposed IADPSG guidelines, although the impact on workload is expected to be substantial (152). The original criteria for diagnosis of GDM were defined solely on the basis of their ability to identify a prediabetic state in the mother (153).
Given the controversy that persists in the international community about the diagnosis of gestational diabetes, there is no clear answer as to what is ideal.
During pregnancy, women should be evaluated and followed by a registered dietitian to ensure that nutrition therapy promotes euglycemia, appropriate weight gain and adequate nutritional intake (154–157).
Insulin If women with GDM do not achieve glycemic targets within 2 weeks from nutritional therapy alone, insulin therapy should be initiated (177,178).
In 2008, Rowan et al (194) studied 751 women with GDM who were randomly assigned to open treatment with metformin (with supplemental insulin if required) or insulin.
When comparing metformin to glyburide, there is a 2:1 failure of control of patients on metformin vs.
The primary goal of intrapartum management is to prevent neonatal hypoglycemia, which is thought to occur from the fetal hyperinsulinism caused by maternal hyperglycemia (202). Neonatal hypoglycemia There has been much disagreement over the definition of neonatal hypoglycemia because of the lack of rigorous scientific studies. Longer term follow-up found that infants with neonatal hypoglycemia had increased rates of neurological abnormalities at 18 months (208,209) and 8 years of age (210).
Risk of neonatal hypoglycemia is related to maternal glucose levels Maternal hyperglycemia during labour, even when produced for a few hours by intravenous fluids in mothers without diabetes, can cause neonatal hypoglycemia (205,211). Insulin requirements decrease intrapartum, and some patients with type 1 diabetes even do not require exogenous insulin to maintain good glucose control during labour (219,220). Breastfeeding Women with GDM may have more difficulty breastfeeding due to increased operative deliveries and obesity.
Long-term maternal risks With the diagnosis of GDM, there is evidence of impairment of both insulin secretion and action (231,232). Long-term fetal risks There is increasing interest in determining how long the adverse effects of diabetes on pregnancy persist.
Information has been collected from the Pima Indians since 1965 examining the impact of maternal diabetes on children and adolescents (270).
Since that time, the great majority of studies (270) continue to show an increased risk of obesity and metabolic abnormalities in childhood extending into adolescence and early adulthood (273–275). How are the long-term consequences of maternal diabetes caused and could they be prevented?
LGA infants of diabetic mothers and accelerated third-trimester growth have widely been found to be independent risk factors for offspring obesity and metabolic syndrome (272–283).
Firm conclusions about the benefits of modifying these risk factors are limited by the lack of intervention studies.
Women with previous GDM should plan future pregnancies in consultation with their healthcare providers (289,290). 1.All women of reproductive age with type 1 or type 2 diabetes should receive advice on reliable birth control, the importance of glycemic control prior to pregnancy, the impact of BMI on pregnancy outcomes, the need for folic acid and the need to stop potentially embryopathic drugs prior to pregnancy [Grade D, Level 4 (11)].
4.Women with type 2 diabetes who are planning a pregnancy should switch from noninsulin antihyperglycemic agents to insulin for glycemic control [Grade D, Consensus].
6.Women should be screened for chronic kidney disease prior to pregnancy (see Chronic Kidney Disease chapter, p. 9.Detemir [Grade C, Level 2 (95)] or glargine [Grade C, Level 3 (94)] may be used in women with pregestational diabetes as an alternative to NPH.
11.Women should receive adequate glucose during labour in order to meet their high-energy requirements [Grade D, Consensus].
12.Women with pregestational diabetes should be carefully monitored postpartum as they have a high risk of hypoglycemia [Grade D, Consensus].
15.All women should be encouraged to breastfeed since this may reduce offspring obesity, especially in the setting of maternal obesity [Grade C, Level 3 (224)]. 17.If there is a high risk of GDM based on multiple clinical factors, screening should be offered at any stage in the pregnancy [Grade D, Consensus].
This article addresses issues related to the screening and diagnosis of diabetes among children. Because many more of the above conditions are met for type 2 diabetes than for type 1, screening efforts are focused on type 2 diabetes. Although screening for type 1 diabetes is not generally done outside of a research context, there are a number of risk factors that are associated with the development of type 1 diabetes.
For a child at high risk (with or without symptoms), fasting hyperglycemia should be tested.
NOTE: In the absence of unequivocal hyperglycemia, these criteria should be confirmed by repeat testing on a different day. Children should be screened if they are at substantial risk for type 2 diabetes, particularly if they are obese or have a family history of diabetes.
It is difficult to distinguish between various forms of diabetes because standard differentials such as ketoacidosis (type 1) or obesity (type 2) can occur in either group.
Laboratory testing for C-peptide, which is formed during conversion of proinsulin to insulin, can differentially diagnose type 1 and type 2 diabetes.
Science, Technology and Medicine open access publisher.Publish, read and share novel research. Type 2 Diabetes Mellitus in Family Practice: Prevention and ScreeningEvans Philip1, Wright Christine, Pereira Gray Denis and Langley Peter[1] St Leonard’s Research Practice, Exeter, United Kingdom1.
Diabetes UK (2006) suggest a fasting capillary blood test can be used for initial screening purposes, although this has lower sensitivity and specificity than venous blood glucose measurement and requires careful interpretation and feedback to the patient. Marteau (1990) notes that the receipt of an invitation to participate in a cancer or general health screening programme can be enough to evoke anxiety for some patients. Screening for type 2 diabetes: an exploration of subjects’ perceptions regarding diagnosis and procedure. Preservation of pancreatic beta-cell function and prevention of type 2 diabetes by pharmacological treatment of insulin resistance in high-risk hispanic women. Acarbose treatment and the risk of cardiovascular disease and hypertension in patients with impaired glucose tolerance: the STOP-NIDDM trial. Comparison of different stepwise screening strategies for type 2 diabetes : Findings from Danish general practice, ADDITION- DK. Age- and sex-specific prevalences of diabetes and impaired glucose regulation in 13 European cohorts.
Our New BMJ website does not support IE6 please upgrade your browser to the latest version or use alternative browsers suggested below. Screening for diabetes implies testing for diabetes in individuals without symptoms who are unaware of their condition.
Therefore, to screen for diabetes and prediabetes, the same tests would be used as for diagnosis of both medical conditions (see Definition, Classification and Diagnosis chapter, p. An individual’s risk of developing type 1 diabetes can be estimated by considering family history of type 1 diabetes with attention to age of onset and sex of the affected family members (2)and profiling immunity and genetic markers (3). Tests for hyperglycemia can identify these individuals, many of whom will have, or will be at risk for, preventable diabetes complications (5,6). Using data collected in 1991, the prevalence of diabetes was assessed in >20,000 individuals diagnosed with schizophrenia. Routine testing for type 2 diabetes is, therefore, justifiable in some but not all settings (18,19).
However, the impact of known risk factors on having undiagnosed type 2 diabetes differs between populations of different ethnic origins, and risk scores developed in Caucasian populations cannot be applied to populations of other ethnic groups (22). Bingley Interactions of age, islet cell antibodies, insulin autoantibodies, and first-phase insulin response in predicting risk of progression to IDDM in ICA+ relatives: the ICARUS data set. At conception and during the first trimester, hyperglycemia increases the risk of fetal malformations. The prevalence of pregestational diabetes has increased in the past decade, primarily as a result of the increase in type 2 diabetes (6). Type 1 diabetes is more often associated with preeclampsia and type 2 diabetes with chronic hypertension.
Microalbuminuria and overt nephropathy are associated with increased risk of maternal and fetal complications (34–39). Some (47), but not all (48), cohort studies have demonstrated an increased risk of malformations. Myocardial infarction in pregnancy is associated with poor maternal and fetal outcomes (51,52). An early working relationship should be established between the woman and the DHC team to optimize care, facilitate the planning of pregnancy, ensure adequate self-care practices and discuss the need for social support during pregnancy.
The risk of severe hypoglycemia ranged from 22% to 71%, with the likely predictors being a history of severe hypoglycemia and hypoglycemic unawareness. Preprandial determinations, which are needed to guide the meal-time insulin dose adjustment and, postprandial testing to achieve targets are associated with less macrosomia and preeclampsia (58,59,76). Intensive insulin therapy with basal-bolus therapy or continuous subcutaneous insulin infusion (CSII or the insulin pump) is recommended to achieve glycemic targets prior to pregnancy.
Therefore, women with type 2 diabetes who find themselves on metformin or glyburide when they conceive should continue these agents until insulin is started. A number of these studies have evaluated metformin for use in ovulation induction and infertility in this population; however, there are conflicting data regarding the benefits of metformin use in this population. The evidence, therefore, does not support the practice of continuing metformin after conception in women with PCOS and normal glucose tolerance.
For GDM, screening programs became widespread despite not meeting many of these traditional criteria and, thus, have led to numerous debates regarding the utility and methodology of GDM screening (116,117). The results of these 2 trials, despite some methodological differences, show a benefit to treatment over no treatment of diagnosed GDM with regard to select perinatal outcomes. This large study (n=23 316) confirmed the findings from 2 previous large-scale, prospective, observational studies (126,127) that the incidence of select adverse maternal and fetal outcomes increases along a continuum of increasing maternal hyperglycemia. The goal of risk factor–based screening would be to ideally identify through historical and clinical risk factors those patients who would benefit most from biochemical screening while allowing those at lower risk to avoid the screening process. Methods for sequential screening include the use of glycosuria, A1C, fasting plasma glucose (FPG), random plasma glucose and a glucose load. The performance of the GCT as a screening test depends on the cutoff values used, the criteria for diagnosis of GDM and the prevalence of GDM in the screened population. An excellent review of the literature on cost effectiveness of different screening strategies for GDM can be found in Health Technology Assessment 2010.
In summary, most cost analysis evaluations support a sequential screening approach to GDM; thus, our preferred approach is to continue with this strategy.
Thus, all of the recent diagnostic thresholds for GDM have been determined by consensus agreement of various national and international professional organizations (see Table 2 ).
Ideally, the diagnostic thresholds would be based on their ability to predict clinically relevant perinatal outcomes, such as perinatal mortality, birth trauma or birth asphyxia. Meal planning should emphasize moderate carbohydrate restriction and distribution over 3 meals and 3 snacks, one of which should be at bedtime.
Both fasting and postprandial testing are recommended to guide therapy in order to achieve glycemic targets (164,165). In some cases, assessment of fetal growth by early third-trimester ultrasound can be used to guide therapy (179,180). Women who are older, are diagnosed earlier than 25 weeks and have higher fasting and postprandial glucose values on their OGTT are less likely to respond to glyburide (187,190). Studies have generally been performed in mothers with pregestational diabetes or insulin-treated GDM. There are very few studies (although many published protocols) as to the best method of managing glycemia during labour (221,222).
Women with GDM should be encouraged to breastfeed immediately after delivery and for at least 3 months postpartum, as this may reduce neonatal hypoglycemia and offspring obesity, and prevent the development of metabolic syndrome and type 2 diabetes in the mother (224–230). These defects persist postpartum and increase the risk of impaired fasting glucose, IGT and type 2 diabetes (233,234). Freinkel (268) extended the original Pedersen hypothesis of fuel-mediated teratogenesis to suggest that abnormal metabolism during pregnancy could have long-term effects on the offspring of diabetic mothers (ODM) (269).
Children whose mothers had diabetes during pregnancy had a significantly higher incidence of obesity and type 2 diabetes that was detectable by age 9 and persisted into adulthood.
Genetics, exposure to abnormal intrauterine metabolism or the family environment all could potentially be involved. Similarly, risk has been shown to be related to maternal glucose levels during pregnancy (281,284,285). Glucose tolerance should be assessed prior to conception to assure normoglycemia at the time of conception, and any glucose abnormality should be treated. Women with pregestational diabetes who also have PCOS may continue metformin for ovulation induction [Grade D, Consensus].
S129) [Grade D, Level 4, for type 1 diabetes (39) ; Grade D, Consensus, for type 2 diabetes]. If the initial screening is performed before 24 weeks of gestation and is negative, rescreen between 24 and 28 weeks of gestation.
Criteria for diagnosing diabetes using fasting plasma glucose testing are listed in Table 2. This test should be performed as described by WHO, using a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water. Symptoms of type 2 diabetes often are slow to develop, whereas type 1 diabetes symptoms usually develop over a short period. Maturity-onset diabetes of the young (MODY) is rare and occurs mainly in whites, but it can affect any ethnic group. Adiponectin and leptin concentrations may aid in discriminating disease forms in children and adolescents with type 1 and type 2 diabetes. Screening for Type 2 DiabetesType 2 Diabetes may well be a suitable disease for screening - it is a serious disease, being associated with many complications, especially in the eyes, heart, kidneys, and limbs and it shortens the expectation of life considerably.
As one might expect, receiving a ‘positive’ result after the screening test can also cause negative emotional reactions. A meta-regression analysis of published data from 20 studies of 95,783 individuals followed for 12.4 years.
The base case model assumed a 50 year time horizon with discounting of both costs and benefits at 3.5%. Screening for diabetes will also detect individuals at increased risk for diabetes (prediabetes) or individuals with less severe states of dysglycemia who may still be at risk for type 2 diabetes.
The loss of pancreatic beta cells in the development of type 1 diabetes passes through a subclinical prodrome that can be detected reliably in first- and second-degree relatives of persons with type 1 diabetes by the presence of pancreatic islet autoantibodies in their sera (4). To be effective, population-based screening would have to involve wide coverage and would have the goal of early identification and subsequent intervention to reduce morbidity and mortality. The rate of diagnosed diabetes was 9% to 14%, exceeding rates for the general population prior to the widespread use of new antipsychotic drugs (27). Screening individuals as early as age 40 years in family physicians’ offices has proved to be useful in detecting unrecognized diabetes (20). Members of high-risk ethnic populations ( Table 1) should be screened for prediabetes and type 2 diabetes using the recommended screening tests, such as FPG, OGTT and A1C. Furthermore, the prevalence of individuals at risk for developing type 2 diabetes varies considerably according to the scoring system.
Chisholm Diabetes, insulin resistance and glucose metabolism in HIV infection and its treatment J.M.
These recommendations have been created in collaboration with the Society of Obstetricians and Gynaecologists of Canada (SOGC).
Later in pregnancy, it increases the risk of macrosomia and metabolic complications at birth (1,2). Recent large studies of women with pregestational diabetes continue to show higher rates of complications compared to the general population, including perinatal mortality, congenital malformations, hypertension, preterm delivery, large-for-gestational-age (LGA) infants, caesarean delivery and neonatal morbidities (7–9). Women who are heavier, younger and smokers, and who have a lower socioeconomic status, lower health literacy and a poor relationship with their healthcare provider, are less likely to receive preconception care (11–14). Other risk factors for hypertension, such as poor glycemic control in early pregnancy, are potentially modifiable. An estimated glomerular filtration rate (eGFR) should be used prior to pregnancy to determine risk (40).
Women with known CVD should be evaluated and counselled about the significant risks associated with pregnancy.
The latter may relate, in part, to the loss of counterregulatory hormones reported in women with pregestational diabetes during pregnancy, particularly growth hormone and epinephrine (65–68). Due to the increased risk of nocturnal hypoglycemia with any intensive insulin therapy, glucose monitoring during the night is often necessary in patients receiving insulin (77).
Women using CSII should be educated about the increased risk of diabetic ketoacidosis (DKA) in the event of insulin pump failure because DKA is a potentially fatal complication for the fetus (86).
Lispro does not cross the placenta except at very high doses (>50 units), similar to human insulin (87). A recent meta-analysis of observational studies showed no adverse fetal outcomes in women taking glargine in pregnancy, while maternal outcomes were similar (94). One cohort study of women with type 2 diabetes found an increase in perinatal mortality in women taking metformin compared with insulin; however, the circumstances surrounding these deaths suggest other confounding factors played a role (102). Several observational studies have suggested that metformin may decrease the rate of spontaneous abortions in women with PCOS, prompting many to advocate the use of metformin up to the end of the first trimester or throughout pregnancy in these women (104,105). However, the considerable data available help to confirm the safety of metformin given during pregnancy. A study looking at weight, height and motor-social development up to 6 months of age in children of mothers taking metformin while breastfeeding showed normal development and no difference from formula-fed infants (111). Recent studies and the publication of new guidelines by the International Association of Diabetes and Pregnancy Study Groups (IADPSG) consensus panel have given us the opportunity to revisit the evidence on screening for GDM (118). These findings support the need for a screening strategy for GDM, a largely asymptomatic condition, as there appears to be a beneficial intervention for patients with the disease. Unfortunately, no outcome-associated glycemic thresholds were identified that could be used to define internationally accepted criteria for the diagnosis of GDM. Aside from the glucose load, all the other methods mentioned have not been adopted due to their poor performance as screening tests in most populations (133–138).
This recommendation is based on a retrospective cohort study in 514 women with a positive 50 g GCT who went on to have a 100 g OGTT (142). The use of the term screening is misleading in this context as this strategy entails performing the diagnostic test on the entire population at risk. Canadian economic data from a prospective, randomized trial of 3 different screening strategies offers relevant information for the Canadian population (151). Hypocaloric diets are not recommended, as they result in weight loss and significant ketosis and are likely inadequate in required nutrients, such as protein and calcium. Thus, until prospective studies of precise targets are available, using the targets in the Maternal-Fetal-Medicine-Unit Network study that were associated with achieving good glycemic control and outcomes appears reasonable (120). The use of insulin to achieve glycemic targets has been shown to reduce fetal and maternal morbidity (178,181).
Despite the glucose levels, some earlier studies report more adverse outcomes in women treated with glyburide compared to insulin (191,192). Metformin (alone or with supplemental insulin) was not associated with increased perinatal complications compared with insulin. Mild neonatal hypoglycemia has been found to be associated with transient abnormalities on physical examination (205), neurophysiological testing (206) and brain imaging (207). These have been observational with no randomized trials deliberately targeting different levels of maternal glycemia during labour.
Rotating intravenous fluids compared with intravenous insulin were no different in controlling maternal glycemia in GDM (223). The cumulative risk increases markedly in the first 5 years and more slowly after 10 years (235,236).
Northwestern University enrolled women with both GDM and pregestational diabetes from 1977 to 1983 and followed their offspring until adolescence. Obesity in adolescence results in an increased risk of metabolic syndrome (277) and coronary artery disease (278).


The issue was addressed in the Pima by studying nuclear families with siblings born within 3 years of each other, before and after the mother developed diabetes.
In view of the known benefits of breastfeeding and of preventing maternal obesity and LGA infants, it would not be ethical to conduct randomized trials deliberately exposing 1 group to suboptimal levels of 1 of these risk factors. Women with microalbuminuria or overt nephropathy are at increased risk for development of hypertension and preeclampsia [Grade A, Level 1 (39,44)] and should be followed closely for these conditions [Grade D, Consensus]. In terms of diagnosis, one big challenge facing clinicians is distinguishing between type 1 and type 2 diabetes in youth. When further diagnostic testing is performed, 85% to 90% generally have serological evidence of an autoimmune pathologic islet cell process. Diagnosing Type 2 diabetes before patients complain of diabetic symptoms – clinical opportunistic screening in a single general practice. It is a condition associated with numerous complications, which may well be present even at the time of diagnosis. Guidance (American Diabetes Association, 2011; Diabetes UK, 2006) exists for health professionals with regard to the interpretation of test results. People are not always reassured, even by a ‘normal’ result, and other adverse psychological effects can occur. However, in a recent large study, one-time screening for glutamic acid decarboxylase antibodies (GADAs) and islet antigen-2 antibodies (IA-2As) in the general childhood population in Finland would identify 60% of those individuals who will develop type 1 diabetes over the next 27 years. However, the high prevalence of hemoglobinopathies among these populations may considerably reduce the accuracy of A1C as a reliable screening tool in these populations. Risk scoring systems must, therefore, be validated for each considered population in order to adequately detect individuals at risk and eventually implement efficacious preventative strategies (23).
Icks High prevalence of undiagnosed diabetes mellitus in Southern Germany: target populations for efficient screening. Waeber Estimating the risk of developing type 2 diabetes: a comparison of several risk scores.
As a result, meticulous glycemic control is required for optimal maternal and fetal outcomes.
Some, but not all, have shown that women with type 2 diabetes are also less likely to receive preconception care (7,15).
Laser photocoagulation for severe nonproliferative or proliferative retinopathy prior to pregnancy reduces the risk of visual impairment in pregnancy (30).
Some (31,32), but not all (33), studies have found that increased urinary protein excretion in early pregnancy raises the risk of developing hypertension.
However, during pregnancy, serum creatinine and not eGFR should be used, as eGFR will underestimate GFR in pregnancy (41,42).
This risk of hypoglycemia may be ameliorated if efforts are made to achieve good glycemic control preconception and by the use of analogue insulins (64,69,70). Continuous glucose monitoring systems may help identify periods of hyper- or hypoglycemia (78,79) and certainly confirm glycemic variability (80). A randomized trial of detemir use compared with NPH in women with type 1 diabetes has recently been completed, with similar maternal and fetal outcomes in both groups (95). In another cohort study, there was an increase in perinatal mortality in women taking sulphonylureas, or sulphonylureas plus metformin compared to insulin, but not in those taking metformin alone (103). However, in a meta-analysis of 17 randomized controlled trials (RCTs), metformin use, either alone or with other fertility drugs, had no significant effect on the abortion risk when used preconception (106). Worldwide, there is currently no agreement regarding the optimal screening strategy for GDM.
Despite this, in 2010, the IADPSG consensus panel decided to use the HAPO data to create new diagnostic thresholds for GDM. One cannot directly infer from these studies that there is utility to screening for GDM as they were not designed to assess screening vs.
In populations that are older and have increased body mass index (BMI), selective screening ultimately leads to a majority of the pregnant population being screened; thus, universal screening is the pragmatic approach accepted in most North American centers.
The 1-step approach includes a 75 g OGTT performed in the fasting state at 24 to 28 weeks of gestation with plasma glucose measured at fasting and 1 and 2 hours after the glucose load.
Unfortunately, in this study, no single threshold could be identified that predicted the primary outcome. Prepregnancy body mass is a potent predictor of birth weight and should be considered when making recommendations about energy intake and rate of weight gain (158).
Although the peak for postprandial glycemia occurs at 69 ± 24 minutes (3) and hence may lend support to a 1-hour target being used, in obesity, this peak appears delayed (172). A variety of protocols have been used, with multiple injections being the most effective (182).
More recent studies have shown glyburide to be a safe alternative with no dose-related increment in neonatal hypoglycemia (193).
There was less severe hypoglycemia in neonates receiving metformin but more spontaneous preterm delivery( i.e. Most have found that there is a continuous relationship between mean maternal glucose levels during labour and the risk of neonatal hypoglycemia with no obvious threshold. The fact that the risk of the child developing diabetes was significantly higher (OR 3.7) in siblings born after the mother developed diabetes demonstrated that intrauterine exposure per se conveyed the increased risk (279). Studies also have found that adequate breastfeeding is associated with a significant decrease in the risk of childhood obesity (223,283,287). However, it seems reasonable to assume that our current efforts at tight control of maternal nutrition and diabetes during pregnancy and promoting breastfeeding will provide benefits throughout childhood and adolescence. In the past, it could be safely assumed that a child presenting with diabetes could be given the diagnosis of type 1 diabetes.
Screening high-risk children every 2 years after age 10 can detect disease at an early asymptomatic stage. Fasting plasma glucose and 2-hr postprandial glucose are used for diagnostic testing, with the former preferred because of cost and convenience. For example, a ‘normal’ result may reinforce an unhealthy lifestyle or perceptions of invulnerability, and make patients less likely to return for future screening (Marteau 1989). At a willingness-to-pay threshold of ?20?000 the probability of the intervention being cost effective was 49%, 93%, and 85% for each of the active screening strategies respectively.Conclusions Screening for type 2 diabetes and impaired glucose tolerance, with appropriate intervention for those with impaired glucose tolerance, in an above average risk population aged 45, seems to be cost effective. In the subsequent ADDITION-Europe cluster randomized trial of intensive multifaceted cardiovascular risk factor management vs. Furthermore, high-risk ethnic groups may have A1C levels that are slightly higher than those of Caucasians at the same level of glycemia, and more studies may help determine ethnic-specific A1C thresholds for diabetes diagnosis (see Definition, Classification and Diagnosis chapter, p. If results of 2 different tests are available and both are above the diagnostic cutpoints, the diagnosis of diabetes is confirmed. A random albumin to creatinine ratio and serum creatinine should be measured each trimester. Thus, the increased risk of malformations may be more related to the hypertension itself rather than a direct effect of ACE inhibitors and ARBs.
Whether closed loop systems will become practical for use in pregnancy remains to be seen (81).
Cohort studies have shown improved A1C levels and less hypoglycemia in women with pregestational diabetes in pregnancy taking lispro compared with human insulin, while fetal outcomes were similar (88–90). In each of the trials in this meta-analysis, metformin was discontinued at the time of diagnosis of pregnancy. There are no studies to date looking at thiazolidinedione use, glucagon-like peptide-1 agonist or dipeptidyl peptidase-4 (DPP-4) inhibitor use while breastfeeding; therefore, they should not be taken during breastfeeding. Universal and selective (risk factor based) screening are the most common methods used, but only 1 randomized trial has compared these 2 strategies (121). It is possible that future analysis of the HAPO data based on GDM risk factors might allow modification of this recommendation (132). Using the data from this study, we need to understand that, by using the sequential 50 g GCT followed by a glucose tolerance test, some 20% of the population will screen positive, of whom 16% will not have GDM. The IADPSG and the American Diabetes Association (ADA) have supported this option (118,122), while some European guidelines recommend the 75 g OGTT only to women with risk factors but use the IADPSG thresholds for diagnosis of GDM (147–149).
The sequential screening strategy was found to be less expensive while having the same diagnostic power as there was no difference in the incidence of GDM in all 3 groups. The continuous association between increasing glucose intolerance and the risk of caesarean section, birth weight >90%, neonatal hypoglycemia and cord C-peptide levels did not permit the determination of new diagnostic criteria. Continuous glucose monitoring systems have been useful in picking up previously undetected hyperglycemia, but it is unproven if they are cost effective (173–175).
A recent systematic review of the literature has shown glyburide and metformin have similar outcomes when compared to insulin therapy (201).
Authors have often chosen 2 levels within the range and shown that there is more hypoglycemia with the higher value, but the studies do not arrive at a common value. Given the lack of studies, there are no specific protocols that can be recommended to achieve the desired maternal glucose levels during labour. While elevated FPG during pregnancy is a strong predictor of early development of diabetes (237,238), other predictors include age at diagnosis, use of insulin, especially bedtime insulin or oral agents, and more than 2 pregnancies (239,240).
They found that aberrant maternal metabolism in the second and third trimesters (most often beta-hydroxbutyrate levels) was associated with reduced intellectual and psychomotor development on a number of tests performed up to age 11.
The focus therefore is on both prevention and early detection by screening, with a view to preventing or delaying complications. Blood glucose tests and oral glucose tolerance tests have no adverse effects for the patient apart from the inconvenience of having blood tests and the very rare complications of venepuncture.There are two broad approaches to screening for Type 2 Diabetes – population or opportunistic screening. Recently, studies in Europe and the USA have specifically explored the psychological effects of undergoing screening for Type 2 Diabetes and these tend to support the conclusions of Marteau’s work. The combined positivity for GADAs and IA-2As had both a specificity and a positive predictive value of 100% (95% CI 59–100%) (5). By discussing pregnancy prior to conception, healthcare providers may be able to improve outcomes by educating women about the importance of strict glycemic control, encouraging folic acid supplementation, discontinuing potentially harmful medications and reducing body weight.
A number of antihypertensive medications are known to be safe and effective in pregnancy, including calcium channel blockers, labetalol and methyldopa. Fetal exposure in the second and third trimesters is clearly associated with a fetal renin-angiotensin system blockade syndrome, which includes renal failure, oligohydramnios, hypotension, intrauterine growth restriction and death (50). Maternal hypoglycemia does not increase the risk of congenital malformations in the offspring (53,71,72) or other adverse outcomes (2).
Data on glargine are more limited (cohort and case control studies), and theoretical considerations make it less desirable; however, no adverse maternal or fetal effects have been found to date. Currently, a large randomized trial is underway to see if adding metformin to insulin will benefit mothers with type 2 diabetes and their infants (MiTy trial).
Other nonrandomized studies have noted benefit in women who used metformin throughout pregnancy (107).
In conclusion, metformin and glyburide can be considered for use during breastfeeding, although further long-term studies are needed to better clarify the safety of these drugs. The most common method of screening is with the stepwise 50 g oral glucose challenge test (OGCT) at 24 to 28 weeks of gestation, followed by an oral glucose tolerance test (OGTT) as the diagnostic test if a certain threshold has been surpassed.
The utility of screening will vary based on the baseline characteristics of the screened population and the country-specific health economics evaluation.
Due to the low sensitivity, almost one-fourth of the patients with GDM will not be diagnosed using this strategy; specifically, the test will not identify those women whose only abnormality is elevated FPG. In March 2013, the National Institutes of Health (NIH) held a consensus development conference to discuss the diagnosis of GDM.
This, in itself, is surprising as one would expect the incidence of GDM to be higher in the universally tested group. Physical activity should be encouraged unless obstetrical contraindications exist or glycemic control is worsened by the activity (159,160).
Women with GDM, in an effort to control their glucose by diet, may put themselves and their baby at risk for starvation ketosis. Although the rapid-acting bolus analogues aspart and lispro can help achieve postprandial targets without causing severe hypoglycemia (181–183), improvements in fetal outcomes have not been demonstrated with the use of aspart or lispro compared to regular insulin (181,182). Other studies have confirmed the safety of metformin with less neonatal hypoglycemia (195). With respect to growth, neonatal macrosomia had resolved by age 1, and weight was not different from controls until age 5. After examining multiple factors, they found that increased BMI was mediated through an intrauterine mechanism (280).
This chapter gives a brief overview of the evidence for prevention of Type 2 Diabetes (behavioural and pharmacological) and describes various approaches to screening, from an international perspective, together with their relative advantages and disadvantages. Approaches to screeningA number of targeted screening programmes have been piloted in the UK, Europe and the USA in the last decade (e.g. This might be important as early detection and treatment could prevent future associated microvascular and macrovascular complications. Ongoing clinical studies are testing different strategies for preventing or reversing early type 1 diabetes in the presence of positive autoimmunity. Of note, a very high proportion of the routine care group also received optimal cardiovascular risk factor management, which may have diluted any potential benefits. Although there are no intervention trials to support larger doses of folic acid for women with diabetes, several factors favour recommending a larger dose.
In women with elevated serum creatinine, however, pregnancy can lead to a permanent deterioration in renal function (46). In later pregnancy, maternal hypoglycemia was associated with a nonsignificant increase in fetal movements (73) and had no impact on fetal heart rate (74) and no long-term consequences for the infant (75), although repeated hypoglycemia and associated loss of glycemic control were associated with macrosomia (68). In the meantime, the use of oral agents is not recommended for glycemic control in women with type 2 diabetes during pregnancy.
These arbitrary thresholds, when applied to the HAPO cohort, led to a GDM incidence of 17.8%. We can, therefore, infer from the results of these management studies, along with the data confirming that the incidence of adverse perinatal outcomes increases as glucose intolerance increases, that identification of women with hyperglycemia in pregnancy has clinical significance. The performance of the 50 g GCT can be improved when slightly more complicated strategies are used, such as factoring in certain risk factors, ethnic background or time from last meal (139–141). The authors also indicate that these results might not be applicable to higher-risk ethnic populations (151). Use of these new thresholds without subjecting them to rigorous clinical evaluation will lead to a significant increase in the number of women labeled as having GDM.
Therefore, an alternative approach would be 1-step 75 g OGTT using the glucose thresholds that result in an OR of 1.75 (IADPSG recommended criteria) ( Figures 1 and 2 ). Older studies raised the possibility that elevated ketoacids may be detrimental to the baby (75,176). A recent analysis reveals that glargine is safe in pregnancy and can be considered an option for pregnant patients (184).
While metformin appears to be a safe alternative to insulin therapy, it does cross the placenta, plus metformin clearance is increased in pregnancy (196). From age 5 through 16, the BMI of ODM (both GDM and pregestational diabetes) was significantly higher than in control subjects (271). Such studies have generally found no lasting or significant adverse psychological effects in terms of anxiety, depression, worry, or perceived quality of life after screening. An estimated 50% of people with diabetes are currently undiagnosed,4 and at presentation around 20-30% have already developed complications.5 An alternative screening approach would be to lower the threshold of the screening test and to screen for impaired glucose tolerance and type 2 diabetes together. Given that the various serological markers are not universally available and in the absence of evidence for interventions to prevent or delay type 1 diabetes, no widespread recommendations for screening for type 1 diabetes can be made. In ADDITION-Cambridge, population-based screening for type 2 diabetes was not associated with a reduction in all-cause, cardiovascular or diabetes-related mortality within 10 years compared to a no-screening control group.
Obesity, which is more common in women with type 2 diabetes, is associated with lower serum folate levels for the same intake, lower intake of folate rich foods and increased risk of neural tube defects independent of glucose (18,19,20). Perinatal outcomes were similar using insulin aspart and human insulin; however, the study was not powered to show differences in these outcomes (91). A recent Cochrane review of randomized trials found that although metformin was effective in improving ovulation rates and pregnancy rates in women with PCOS, both alone and in combination with clomiphene, this did not translate into a significant increase in live births (108).
As hyperglycemia in pregnancy is an asymptomatic condition, diagnosis is dependent on some form of screening. As with all aspects of hyperglycemia in pregnancy, there is evidence that along a continuum of GCT results without a diagnosis of GDM, there is an increase in certain adverse perinatal outcomes (146).
This draft statement stated that, as of that time, the NIH panel did not find sufficient evidence to support adopting a 1-step approach, such as that proposed by IADPSG (150).
This might prove to have a clinical benefit, but there is also the possibility of causing harm through unnecessary interventions, increased anxiety and an effect on women’s perceptions of their health. While the clinical significance of these findings are doubtful, it appears prudent to check that urine ketones are negative when focusing on diet therapy for GDM.
A recent Canadian review of rapid and long-acting basal analogues in GDM for glycemic control and hypoglycemia did not shown superiority (185).
Results of the offspring follow-up of the Metformin in Gestational diabetes trial (Mig TOFU), expected in several years, will provide more data on the long-term safety of metformin. The international guidance for screening for Type 2 Diabetes will be reviewed and a summary of the evidence relating to the psychological effects of screening, as well as the costs and cost-effectiveness of the various types of screening programmes, will be presented.2.
Population screeningPopulation screening, as its name implies, is based on a defined population and aims to screen every person in this population (Engelgau et al., 2000). Many have employed a ‘stepwise’ approach, whereby participants progress through increasingly invasive screening procedures until they are diagnosed with diabetes or found not to have the condition. As well as allowing for earlier diagnosis of type 2 diabetes, interventions can be administered to those identified with impaired glucose tolerance to attempt to delay the onset of type 2 diabetes.
However, the low rate of type 2 diabetes in the screened population (3%) was likely too small to affect overall population mortality (11). Finally, glucose levels in obese, nondiabetic pregnant women were slightly higher than their lean counterparts (5). Using a mathematical model, a 5 mg intake will be more effective in reducing neural tube defects in this vulnerable population (21).
At this point, there is no evidence supporting a specific cutoff value of the 50 g GCT to diagnose GDM. Some women with GDM, especially lean women <30 years of age who require insulin during pregnancy, progress to type 1 diabetes (244,245). The rationale for preventing Type 2 Diabetes and its complicationsThe prevalence of diabetes, particularly Type 2 Diabetes, is increasing on a worldwide scale.
One study, which interviewed people shortly after they underwent screening tests (Adriaanse et al., 2002), found most participants had positive views of the screening process and had not found it burdensome. A recent systematic review and meta-analysis of intervention trials for prevention of type 2 diabetes6 found both lifestyle and pharmacological interventions significantly reduced the risk of type 2 diabetes in people with impaired glucose tolerance.As no definitive trials have examined the effectiveness of screening for type 2 diabetes or impaired glucose tolerance,7 8 assessment of such policies has so far been conducted through simulation studies. Nonetheless, there is no current evidence of clinical benefit to support a strategy of population-based screening for type 2 diabetes.
Metformin also has been associated with improvement in other pregnancy outcomes, including prevention of GDM, in observational studies (109). Women with positive antibodies (anti-glutamic acid decarboxylase (anti-GAD), anti-insulinoma antigen 2 (anti-IA2)) are more likely to have diabetes by 6 months postpartum (246). In either case, a suitable test such as a screening blood glucose test is offered to a defined population. Most individuals who had been newly-diagnosed with diabetes did not feel alarmed or concerned about their results. Several decision models have been compiled that have assessed either the clinical and cost effectiveness of interventions to prevent type 2 diabetes9 10 11 12 13 14 15 16 or strategies for screening and early detection of diabetes.7 17 18 19 20 Previous models of screening for type 2 diabetes alone have generally assessed the impact of early treatment on cardiovascular events, though some additionally included microvascular events such as retinopathy. However, in a recent, randomized, placebo-controlled trial of metformin treatment started in the first trimester of pregnancy in women with PCOS, metformin failed to reduce the rates of preeclampsia, GDM, preterm delivery or a composite of the 3 outcomes (110).
There are no data regarding the performance of combinations of risk factor–based screening and a 75 g OGTT or sequential 50 g GCT followed by a 75 g OGTT using the new IADPSG criteria. Postpartum testing is essential to identify women who continue to have diabetes, those who developed diabetes after temporary normalization and those at risk, including those with IGT. Many appeared to believe they had a ‘mild’ version of the condition that they could control, although they felt the required lifestyle changes would have a significant impact on their life. Overall most of the models produced favourable results for screening, but cost effectiveness varied with age group screened and the population targeted for screening.
Only 1 study to date has looked at longer-term outcomes in women with PCOS taking metformin in pregnancy.
However, many women do not receive adequate postpartum follow-up, and many believe they are not at high risk for diabetes (247–249). For example between 10% and 20% of patients aged 60 to 79 years in the European prevalence study (DECODE) had diabetes (DECODE Study Group, 2003).
However, the yield was small as many people at low risk were approached and some of those detected failed to consult their GP. A recent alternative approach has been the use of online self-completion risk tools to determine a person’s risk of diabetes and hence the need for further action. People whose test results were normal reported feelings of relief or reassurance but saw no reason to change their lifestyle. This small study found no increase in the rate of abnormal growth and motor development in infants at 18 months of age (111). Models used data from various sources from published trials, epidemiological studies, and national statistics. It is essential that the importance of follow-up be explicitly communicated with women and their caregivers who are responsible for postpartum testing.
It has been estimated that having diabetes reduces life expectancy by 17 years in males and 20 years in females, who are diagnosed with the condition at the age of 45 years (Yorkshire & Humber Public Health Observatory, 2007).
Community screening could be cost-effective if the prevalence of Type 2 Diabetes in the community was extremely high, although this is rarely the case. It is also generally acknowledged that a large number of patients with Type 2 Diabetes remain undiagnosed. The populations most often identified for screening include people selected because they have one or more risk factors for Type 2 Diabetes.
If the results of the initial blood test fall within the normal range, the participant does not progress to the next level, but may receive lifestyle advice.
All models compared a strategy of interventions against no interventions, rather than screening for impaired glucose tolerance followed by interventions, compared with no screening. These most commonly include older age, obesity, a family history of diabetes, and hypertension.
If the results of the initial test reveal glucose levels above a specified threshold, participants are invited back for further testing. All but one model simulated populations where all individuals had impaired glucose tolerance at the start of the model and the end state was development of diabetes, or death, hence only a limited section of the disease pathway was modelled. Postnatal fasting blood glucose has been the most consistently found variable in determining women at high risk for early postpartum diabetes (254). This approach increases the likelihood of finding new cases and so improves the efficiency of the screening process.Risk factors are most commonly known to GPs.
At that stage, the screening test may require the patient to fast for a prescribed period prior to the blood sample or undergo a more complex and lengthy screening process, such as the oral glucose tolerance test.Uptake of screening has varied across the studies and this may be a reflection of the type of test offered, how the invitation is made and where the testing takes place.
The economic cost of screening for Type 2 DiabetesEconomic modelling studies have been conducted to estimate the cost-effectiveness of screening for Type 2 Diabetes and Impaired Glucose Tolerance.
Also the models did not take into account that screening for impaired glucose tolerance will at the same time allow individuals with undiagnosed diabetes to be identified, thus allowing for early treatment and possibly reducing rates of complications. They are not known to hospitals, as they do not hold the medical records of populations, only those people referred to them.
In one study (O’Connor et al., 2001), the uptake of an initial random blood glucose test (offered via letter) was 44%. In the UK, decisions about funding of interventions are made by the National Institute for Health and Clinical Excellence (NICE), based on cost-effectiveness. Hence, while these studies offer an assessment of the cost effectiveness of interventions for prevention of diabetes, none assessed the impact of screening followed by interventions on the whole disease pathway.
Women should be counselled that the recurrence rate of GDM is high, from 30% to 84%, in subsequent pregnancies (258,259).
Patients who eventually develop Type 2 Diabetes often pass through a phase of intermediate hyperglycaemia when their blood glucose levels are elevated but not above the diagnostic threshold for Type 2 Diabetes. Hence, population screening nowadays is most commonly based on people selected from the population registers of people registered with family practices. Where random capillary blood tests were offered, however, uptake was around 60-70% (Echouffo-Tcheugui et al., 2009). This body considers that interventions below an incremental cost-effectiveness ratio (ICER) threshold of ?20,000 to ?30,000 per quality-adjusted life-year (QALY) are cost-effective (National Institute for Health and Clinical Excellence, 2004). These intermediate states are collectively called Prediabetes and include Impaired Fasting Glucose diagnosed on a fasting plasma glucose test or Impaired Glucose Tolerance diagnosed on an oral glucose tolerance test. This has meant that most of the research reports have come from those countries in which the health system is based on family practices, i.e. In one study, the reported uptake of a fasting capillary blood glucose test offered directly by the GP was 90% (Woolthuis et al., 2009). One systematic review and economic modelling exercise (Waugh et al., 2007), which included four studies, reached the conclusion that screening for diabetes appeared to be cost-effective for people aged 40-70 years. We compared these three active screening strategies against a fourth strategy of no screening (current practice). Given the increased risk of CVD with metabolic syndrome, consideration should be given for screening for all components of metabolic syndrome in the postpartum care of women with GDM, specifically if there is a family history (263,264).


Australia, Canada, New Zealand, the Netherlands, the UK, Denmark, and registration-based systems in the USA.Population screening has several important advantages. Whilst screening was more cost-effective for the older age bands (50-69 and 60-69 years), even for people aged 40-49 years, the ICER for screening (when compared to a policy of not screening) was ?10,216 per QALY.
The full pathway from screening, to interventions and treatment for type 2 diabetes, all the way through to death, was modelled.
High C-reactive protein, high low-density lipoprotein, fibrinogen and uric acid have been described postpartum in women with a history of GDM (265).
Prediabetes carries an increased risk of progression to Type 2 Diabetes although this can vary widely, dependent on ethnicity and other factors (Unwin et al., 2002). It is mathematically precise, readily reproducible, and can operate largely independent of the clinical skills of the doctors and nurses in the family practices. Screening was found to be more cost-effective for people who were hypertensive and obese and, for many groups, the costs of screening were offset by lower treatment costs in the future. This model directly compares the two alternative approaches of screening for type 2 diabetes alone or screening for impaired glucose tolerance and type 2 diabetes together.
Education on lifestyle modification to prevent diabetes and CVD should begin in pregnancy and continue postpartum.
It is easy to transpose arrangements across areas and countries.Population screening has several important disadvantages. The St Leonard’s Practice approach to screening for Type 2 DiabetesThe system of screening for Type 2 Diabetes in the St Leonard’s Practice, Exeter, UK is one special form of clinical opportunistic screening (Evans et al., 2008). When modelling the effectiveness of interventions, we used all data from relevant randomised controlled trials6 and included uncertainty around model inputs when appropriate. Awareness of exercise for prevention of diabetes is low (266), and emphasis on targeted strategies that incorporate women’s exercise beliefs may increase participation rates (267). Unless whole community populations are used, various techniques have to be employed to determine potential sub-groups at risk.
When comparing a policy of not screening to one of screening for Type 2 Diabetes and Impaired Glucose Tolerance, there were differential costs for each QALY gained, depending on whether diagnosis of Impaired Glucose Tolerance was followed by lifestyle interventions or by pharmaceutical interventions.
By carrying out several sensitivity analyses we investigated the essential elements that affect the cost and clinical effectiveness of different screening policies.MethodsThe hybrid model consists of a decision tree and a Markov model (fig 1)?. The process relies on the clinical alertness of the GPs and practice nurses, and the efficient protocol-driven screening of patients with chronic conditions known to be associated with Type 2 Diabetes.
The costs per QALY gained were ?6,242 for screening followed by lifestyle interventions, and ?7,023 for screening followed by pharmacological interventions. The decision tree comprises three main arms, representing no screening, screening for undiagnosed type 2 diabetes, and screening for impaired glucose tolerance and undiagnosed diabetes, with either lifestyle or pharmacological interventions applied in those with impaired glucose tolerance. The doctors and nurses screen adult patients with cardiovascular or cerebrovascular disease, hypertension, hypercholesterolaemia, obesity, recurrent skin infections, or a positive family history of diabetes. In contrast, the cost-effectiveness of a policy of screening for Type 2 Diabetes only was less certain.
Individuals who have already been identified as having type 2 diabetes are excluded from the screening process. In the Finnish Diabetes Prevention Study, this was achieved by offering detailed and individualised counselling to achieve set lifestyle goals.
However, there are always people, including those at risk, who decline to accept the offer of screening for a variety of reasons. Its advantages are that it eliminates another layer of costs that arise from the involvement of an external agency, such as a university or medical school. Here, compared to a policy of not screening, the estimated costs for each QALY gained in respect of screening for Type 2 Diabetes alone were ?14,150.
The decision tree uses prevalence of impaired glucose tolerance and undiagnosed type 2 diabetes and estimates sensitivity and specificity of a screening test to determine how many individuals from the population start in each state of the Markov model. Prolonged engagement with a dietary counsellor was needed – for example, the median number of sessions per participant was 20 (Tuomilehto et al., 2001).
The process then involves communication with the people in the target population, usually by writing to them and offering them an appointment. It also means that people from external organisations do not see confidential medical records. The results of the above studies suggest that it may be more cost-effective to screen for Type 2 Diabetes and Prediabetes, rather than Type 2 Diabetes alone. The Markov model consists of seven states: normal glucose tolerance, undiagnosed impaired glucose tolerance, diagnosed impaired glucose tolerance, death, and three states for people with diabetes (undiagnosed, diagnosed clinically, or diagnosed through screening, either from a screening test or because they are diagnosed with impaired glucose tolerance initially and hence enter a surveillance programme). Some people will want to change their appointment and staff of the practice need to accommodate this.
A recent meta-analysis has shown that lifestyle interventions can produce a 50% relative risk reduction in the incidence of Type 2 Diabetes at one year (Yamaoka & Tango, 2005).
In one US study (O’Connor et al., 2001), which used a two-step screening protocol (random blood glucose followed by oral glucose tolerance test), one new case of diabetes was identified for every 40 high-risk patients screened.
Whether type 2 diabetes and impaired glucose tolerance are diagnosed or undiagnosed determines whether the patients receive relevant treatments or interventions, and they are modelled accordingly in terms of transition rates to other states.
It is possible to maintain the system year after year and it has been so maintained in this practice since 1987 (Evans et al., 2008). The uptake of screening was relatively low (44% of patients who were invited attended) and the screening costs per new case were estimated at $4,064 per new case identified. For example, individuals identified with impaired glucose tolerance receive an intervention and the estimated intervention effect slows their progression to development of diabetes.
We subsequently developed an educational package for patients with Prediabetes and their healthcare professionals.
Then, if the screening process is separate from the clinician, the clinician has to be informed and take action.
Clinical opportunistic screening has the advantage that, since so many blood tests are taken nowadays in family practice, it is often possible to add the blood glucose screening test to samples being taken already, thus saving the patient an additional blood test. More recently, a Danish study (Dalsgaard et al., 2010) has compared three different stepwise screening strategies for Type 2 Diabetes.
In some US studies, primary care clinicians have not always responded appropriately (Ealovega et al., 2004). In the first strategy, diabetes risk questionnaires were sent by the family practice to people aged 40-69 years and those found to be at high risk were asked to contact their GP to arrange a screening test. It is generally acknowledged that the intensity of the lifestyle intervention delivered in these trials is just not feasible in routine practice (Heneghan et al., 2006). There may be a difference in attitude to those tests initiated by clinicians themselves and those tests initiated by others.
This strategy detected new cases of Type 2 Diabetes in 0.8% of the target population, at a cost of €1,058 (US$1,535)” per case. When more than one estimate was available for a parameter, we pooled estimates using a Bayesian random effects meta-analysis within the comprehensive decision model.
It is inevitable that population screening carries administrative costs over and above the cost of the screening investigations.
Its main advantage internationally is that the method is more easily reproducible in family practices around the world. Model results include both clinical and cost effectiveness outcomes, with cost per quality adjusted life year (QALY) being the primary outcome. Nevertheless, in the UK, the National Health Service has recently instituted a comprehensive vascular risk assessment programme, known as ‘NHS Health Checks’ (Department of Health, 2008). All that is needed is an enthusiastic family practitioner or nurse and an efficient computerised medical record system.
In these approaches, people who were consulting their GP were asked to complete the risk questionnaire in the waiting room and were either offered a screening test during the consultation (OP-direct) or asked to return for a fasting screening test at a subsequent consultation (OP-subsequent).
Prevention of the complications of Type 2 DiabetesOnce a patient has developed Type 2 Diabetes, the major aim of clinical care is to prevent complications and morbidity related to the disease. These checks are offered to patients aged 40 to 74 years old who do not have existing vascular disease or diabetes. The commonest complication of Type 2 Diabetes is cardiovascular disease (American Diabetes Association, 2011) manifested as coronary artery disease, peripheral vascular disease or carotid artery and other cerebrovascular diseases. This is a two-step process and diabetes risk is estimated using a self-completed questionnaire, followed by a blood test if appropriate. The disadvantages of the St Leonard’s system are that the intervention is not standardised and that there are variations between the six doctor partners operating it. The authors concluded that opportunistic screening can identify a similar proportion of new cases as mail-distributed questionnaires, but at lower cost.5.
Data for the decision tree—that is, test sensitivity and specificity and prevalence of impaired glucose tolerance and type 2 diabetes—were taken from the screening those at risk (STAR) study.24 For this study, individuals aged 40-75 (white) or 25-75 (non-white) from 15 general practices in Leicestershire who had at least one recognised risk factor for type 2 diabetes were invited for screening. It is generally acknowledged that patients with Type 2 Diabetes have a raised cardiovascular risk and this may well be present before a clinical diagnosis is made (Hu et al., 2002). It is envisaged that the whole of this age group in the population will be screened once every five years.
It is not yet known how easy it will be to roll it out into other family practices more widely and it may be difficult where morale is low or burnout amongst the doctors is a serious problem (Soler et al., 2008). ConclusionsThe worldwide epidemic of diabetes, mainly Type 2 Diabetes, calls for a major response as, in some countries, prevalence now exceeds 10% of the whole adult population. Risk factors included a known history of coronary heart disease, hypertension, dyslipidaemia, cerebrovascular disease, a first degree relative with type 2 diabetes, and a body mass index (BMI) >25.
Some studies have shown that this risk is equivalent to that of a patient of the same age who does not have diabetes but has already had a coronary event (Haffner et al., 1998).
Clinicians are seeking to prevent the condition developing and to screen for undiagnosed cases.
Therefore the screening data included in the primary model were from a population considered to be “at risk” of type 2 diabetes. Hence, Type 2 Diabetes is often termed a “coronary risk equivalent“, although this has been contradicted recently in a systematic review and meta-analysis (Bulugahapitiya et al., 2009).
Hence, one profound implication is that population screening may well be too costly to be undertaken in developing countries and this is doubly serious as many Asian countries have some of the highest levels of prevalence of Type 2 Diabetes in the world, e.g.
Since Type 2 Diabetes is increasingly managed in family practice or primary care, education and support is important.Prevention of Type 2 Diabetes is now possible through lifestyle alteration but, so far, only after expensive interventions. However, what has yet to be definitively established with regard to screening is whether early diagnosis reduces the risk of complications developing.
We calculated utilities for those with undiagnosed and screen detected diabetes from EQ-5D data, using data on individual patients made available by the Leicester arm of the ADDITION study.42 The data were of a screen detected sample population with type 2 diabetes at baseline.
Clinical opportunistic screeningClinical opportunistic screening is quite different from population screening and is a form of clinical case finding.
Once Type 2 Diabetes is diagnosed, health professionals can then intervene as early as possible, before symptoms develop, in order to prevent complications. For people with clinically diagnosed diabetes, utilities were taken from those reported by the UK prospective diabetes study as this comprised a clinically detected sample.43 The utility for undiagnosed diabetes was kept constant for the whole duration spent in this state as we assumed that if complications developed, which reduced the quality of life, then a diagnosis would be made.
For the states of clinically and screen detected diabetes we needed to account for the fact that duration of diabetes would lead to an increased number of complications and hence a reduction in the utility value.
Effectiveness of treatment of Type 2 DiabetesEffective treatments for the disease are available through lifestyle advice, oral hypoglycaemic drugs, and insulin. The key difference from population screening is that the patient, rather than the clinician, makes the appointment.
Population screening is likely to be introduced in richer countries and has recently started in the UK.
This was done by using reported complication rates, modelled for duration of diabetes and adjusted for estimated HbA1c concentrations in each group and their estimated effect on utility values.43 44 Hence, utilities decreased for each year of duration of diabetes, to reflect increasing incidence of complications. In clinical opportunistic screening, the patient makes the appointment to go to the family practice and then the clinically alert doctor or nurse takes advantage of the patient’s presence in the consulting room to offer screening, based on their risk factor profile. Clinical opportunistic screening in family practice offers an important alternative approach since it may well be more cost-effective, provides the quickest route to treatment, and can detect two-thirds of all new cases of Type 2 Diabetes in a defined population. Because of a higher predicted HbA1c concentration, the utility value was lower at diagnosis and decreased marginally more rapidly in individuals clinically diagnosed compared with those who were screen detected.Economic variablesWe estimated costs from various sources. This process has a long tradition in family practice and the whole basis of determining how many people smoke, drink heavily, are overweight or obese, or have raised cholesterol levels has been done in family practices without any national screening programmes. However, the effectiveness of this type of screening in routine care without extra resources has only been demonstrated in one practice and needs replication. Screening costs included the costs of an initial screening test of fasting plasma glucose and a confirmatory oral glucose tolerance test in those who tested positive. As yet, there are no long-term studies of the effectiveness of treatment after diagnosis of Type 2 Diabetes in screened and unscreened groups, so health economic simulations are needed - with their accompanying assumptions.These models use data from the UK Prospective Diabetes Study (UKPDS, 1998) which showed that intensive treatment of Type 2 Diabetes reduced the risks of microvascular complications but not macrovascular events.
Since more clinical conditions are screened for opportunistically than are screened for by formal population programmes, opportunistic screening can be seen as the usual method of screening. If the early reports are confirmed, then clinical opportunistic screening warrants further consideration as an affordable alternative to population screening, particularly in the developing world. However, subsequent follow up after the trial had finished did show a reduction in macrovascular events in the intensive arm (Holman et al., 2008). National guidance for the effective treatment of Type 2 Diabetes in primary and secondary care exists in the UK (National Collaborating Centre for Chronic Conditions, 2008; National Institute for Health and Clinical Excellence, 2009) and in the US (American Diabetes Association, 2011). The introduction of computer systems in UK family practices (since the 1980s) has enabled generalist doctors and nurses – for the first time – to organise, handle, and retrieve data live during consultations. AcknowledgementsWe acknowledge with thanks the assistance of Ms Beverley Berry, Information Manager at the Royal College of General Practitioners, London, who provided references for reports relating to early community screening programmes in Rotherham, Bedford and Birmingham. For people with diagnosed diabetes, we took average annual costs of antidiabetic treatment, implementation of treatment, and costs of complications from the UK prospective diabetes study.47 For the people with diabetes detected at screening, in whom we would expect costs of complications to be lower, we used costs from the intensively treated arm of the UK prospective diabetes study. These guidelines are evidence-based and should improve outcomes in patients with Type 2 Diabetes. Computers have made the family practice consultation much more efficient and opportunistic screening is one aspect of this.Clinical opportunistic screening has several advantages. For those with clinically diagnosed diabetes, which represents how individuals are diagnosed currently, we used the reported costs of the conventionally treated group.
Effective treatments are targeted at optimising cardiovascular risk factors, including serum lipids, HbA1c and blood pressure.
Firstly, this process eliminates most of the costly administrative overheads associated with population screening. All costs are reported in 2006 UK ?, standardised by using inflation indices.45Sensitivity analyses and model extensionsWe carried out sensitivity analyses using a range of values of prevalence of disease, as well as compliance levels to both screening and interventions. In addition, GPs in the UK also receive incentivised payments under the Quality and Outcome Framework when patients with Type 2 Diabetes reach the glycaemic, blood pressure and lipid targets (Roland, 2004).3. Secondly, since the offer of screening is made within a therapeutic and trusting patient-doctor relationship, acceptance rates are generally high.
Changing prevalence allows us to assess the effectiveness of the screening strategies for different “at risk” populations. An important advantage is that the screening process is offered by the doctor who will care for the patient if the disease is diagnosed, so that, if the test is positive, treatment can start immediately. The effects of compliance to both screening and interventions were also important as we assumed 100% compliance to both in the base case model, which could never be achieved in practice.To evaluate the robustness of the model we also carried out sensitivity analyses on model inputs, particularly those that were estimated from only one or two sources or were thought to be important drivers in the model. An examination or a test is offered to asymptomatic people “to classify them as likely or unlikely to have the disease that is the object of screening” (Morrison, 1998). Thirdly, the relatively high contact rate that people have with their primary health care team underpins clinical opportunistic screening.
These were sensitivities of screening tests, costs of interventions, costs of diabetes, effectiveness of interventions, previous distributions on the standard deviations between studies of the four meta-analyses run within the model, and the time horizon the model was run for.For the base case scenario we considered only a one-off screening at age 45. People who are likely to have the disease are then investigated further to arrive at the final diagnosis. The model was extended further to assess the impact of having one or two additional screenings, at age 50 and 60. This was done by applying the test sensitivities from the STAR study to the numbers in the states of undiagnosed impaired glucose tolerance and type 2 diabetes at the corresponding model cycle and moving the individuals to the relevant diagnosed state.Though the base case model used prevalences and test sensitivities and specificities of a white population, the effect of screening a South Asian or a mixed race population is also relevant in the UK. An early diagnosis and treatment activity applied in large groups is often described as ‘mass screening’ or ‘population screening’ (Morrison, 1998). For example, GPs are spending more and more of their time seeking to alter risk factors for disease. South Asians are thought to have a greater risk of type 2 diabetes, with a greater prevalence of impaired glucose tolerance and a higher transition rate to type 2 diabetes. Population screening in medicine was introduced in the mid-twentieth century and was applied to a number of diseases including tuberculosis, and more recently to cervical cancer, breast cancer and colon cancer.
They screen for and increasingly find and then treat hypertension, itself a risk factor for Type 2 Diabetes and also for obesity which is all too obvious to the clinician. It was also attempted for diabetes.There are two inevitable consequences of all screening programmes, namely the occurrence of what are called ‘false positive’ or ‘false negative’ results.
Other risk factors such as a positive family history may be very well known too as the family doctor will have often treated the older family members for diabetes and may still be doing so.
Discounted costs for each QALY gained, compared with no screening, were ?14?150 (€17?560; $27?860) for type 2 diabetes screening, ?6242 for screening for diabetes and impaired glucose tolerance with lifestyle interventions, and ?7023 for screening for both diabetes and impaired glucose tolerance with pharmacological interventions. False positives are people whose test is positive for the disease being sought but who prove not to have the disease. Fifthly, this is the only system which can be undertaken in developing countries and is possible wherever there are generalist doctors. Costs were lower in the undiscounted model: ?8681, ?2863, and ?3429 for every QALY gained, respectively. At a willingness to pay threshold of ?20?000 per QALY the probability of each strategy being cost effective was 49% for screening for type 2 diabetes only, 93% for screening for both diabetes and impaired glucose tolerance and lifestyle interventions, and 85% for screening for both diabetes and impaired glucose tolerance and pharmacological intervention. People classified as false negative are those who actually have the disease but the test fails to detect it. Realistically, it cannot be expected to cover the entire at-risk population and it is dependent on the patient consulting for some reason.
Evaluation of screening programmesBefore any screening programme is introduced, its advantages and disadvantages must be carefully assessed. Both the intervention strategies showed potential benefits in terms of average years spent without diabetes and cases of diabetes prevented.
The general principles of screening were initially set out in the late 1960s (Wilson & Jungner, 1968).
This is not standard, and there are inevitable variations in clinical skills, which means variations in the screening process being delivered. Although clinical effects seem small, it must be remembered they are average gains across a population, in which only 17% had either impaired glucose tolerance or undiagnosed type 2 diabetes at the time of screening.Tables 3? and 4? show the results of the more important sensitivity analyses (undiscounted). Since then, the criteria have been updated (UK National Screening Committee, 1998) and programmes now need to meet a number of criteria. The offer of clinical opportunistic screening is a judgement and different clinicians will make different judgements at different times. Increasing the prevalence of impaired glucose tolerance and type 2 diabetes decreased the QALYs and increased total costs of each screening strategy.
These broadly relate to the health condition, the screening test, the availability of effective treatment, and the screening programme itself.
Figure 2 outlines our summary of the criteria currently used by a variety of international health organisations to evaluate population screening. Hence, they have been criticised by some as inefficient (Law, 1994) and can be seen as untidy, and potentially unpredictable. Increasing the costs of both lifestyle and pharmacological interventions by a factor of 10 reduced the probabilities of cost effectiveness of their respective screening strategies to 73% and 93%, at the willingness to pay threshold of ?20?000. Whilst Type 2 Diabetes meets many of the criteria for screening, the main argument against population-based screening is that uncertainty remains about the true benefits arising from the early detection of Type 2 Diabetes through such programmes. International guidelines on screening for Type 2 DiabetesWhilst there is not yet sufficient evidence to support the introduction of general population screening, there is broad support for screening programmes that focus on defined sub-groups of the population who are at higher risk of developing Type 2 Diabetes. Increasing the costs of diabetes by a factor of two reduced the probability of cost effectiveness to 49% for screening for type 2 diabetes only, 93% for screening with lifestyle interventions, and 85% for screening with pharmacological interventions at the same threshold. A number of organisations have issued position statements relating to targeted or opportunistic screening for Type 2 Diabetes (e.g. As we increased the time horizon the model was run for, the probability of the three active screening strategies being cost effective compared with no screening increased. This is because the benefits of screening or interventions are not all immediate and most occur in later years of the model, when type 2 diabetes is either delayed or complications are reduced through early diagnosis and treatment.
Who should be offered screening and how frequently?It is generally accepted (American Diabetes Association, 2011; Diabetes UK, 2006) that clinical judgement and patient preference should guide decisions about screening for Type 2 Diabetes.
Overall, the model’s conclusions were robust to changes made to the sensitivity analyses, giving strength to the conclusions.Tables 5 and 6 give the results of the model extensions as undiscounted estimates? ?. However, Diabetes UK (2006) and the American Diabetes Association (2011) recommend that health professionals should consider proactively screening adults at risk of developing the condition every three years. Our model considered the whole screening and intervention pathway from screening to death and a comparison of different approaches to diabetes screening and prevention.Differences in clinical outcomes between the no screening strategy and the three active screening strategies were small, partly because they were reported as an average for a screened population with mixed glucose tolerance. Also microvascular and macrovascular outcomes were not measured individually in this model, which might show benefits from the early detection or delay of type 2 diabetes.Our model makes several assumptions. Where should screening take place?Currently, the consensus view is that screening should take place in a clinical setting, with testing offered by health care providers, based on an assessment of the individual patient.
No transition was allowed from normal glucose tolerance to diabetes without first passing through impaired glucose tolerance. This is because it is clinically unlikely that an individual would change from normal glucose tolerance to diabetes within a year, which is one model cycle. No transition was allowed from diabetes back to impaired glucose tolerance or from impaired to normal glucose tolerance. Diabetes UK (2006) supports community screening for patient groups who do not routinely access family practice services, provided that the screening process is guided by clear protocols, staff receive appropriate training, and good medical support is available from local health services. This is clinically accurate because once an individual has a diagnosis of type 2 diabetes, even if their glucose tolerance improves, they are still clinically defined as having diabetes.
In contrast, the American Diabetes Association (2011) does not recommend community screening, even for high-risk populations, because there is a risk that those screened may not seek or be able to access appropriate follow-up and care. Although 10 year averages of HbA1c concentrations were used for people with diabetes, when we ran our model for longer time horizons the HbA1c concentrations were potentially underestimated, which means complication rates and their effects on utilities and mortality might also be moderately underestimated. Which screening test should be used?There is insufficient evidence to identify a single ideal screening test (Waugh et al., 2007). Further data are needed on how HbA1c concentration could be expected to increase over time to allow more accurate modelling.Screening costs incorporated within the model included only costs of the test and the nurse’s time, therefore representing the costs of opportunistic screening.
A range of tests exist which might be used for screening purposes and these vary in their sensitivity and specificity, as well as their convenience, acceptability and cost (Cox & Edelman, 2009).
We did not include further costs of establishing systematic screening, such as the identification of eligible patients, the issuing of invitations to screening, and the chasing up of non-attenders. In practice, these additional costs would be small for each individual screened, particularly if screening was incorporated into current health checks. When modelling costs of treatment and complications associated with diabetes, we used the average yearly costs taken from the UK prospective diabetes study.
As costs would be expected to start off low and then increase, this means that costs of diabetes might be initially overestimated when an individual receives the diagnosis and eventually underestimated by this model.
In addition, as average costs were used, we did not account for issues of competing risks of complications associated with diabetes. It is easier and faster to perform in clinical settings, more convenient and acceptable to patients, and less expensive than other tests.
Unfortunately, yearly data on costs of diabetes, or how the occurrence of complications impacted on the probability of other complications occurring, were not available to enable us to model costs more accurately. The latest US guidance (American Diabetes Association, 2011) also states that the HbA1c and 2-hour 75g oral glucose tolerance test are appropriate tests to screen for diabetes.
The issue of competing risks arises not just for costs but also for the annual probabilities of complications. European guidance has tended to encourage the use of the oral glucose tolerance test as the gold standard diagnostic test (Waugh et al., 2007).
Ideally, we need data on individual patients to enable the correlation structure in both the probabilities and costs to be appropriately accounted for.As we ran the model for a time horizon of 50 years, the screened population (aged 45 at the start) aged with each cycle of the model, thus, when possible, we incorporated time dependent model parameters.
For some parameters, such as the treatment intervention effects, however, we assumed that the effect was constant over time. Additionally, although compliance was high in the intervention trials from which estimates of their effectiveness were obtained, it is still to be determined whether compliance could be maintained outside a trial setting.
Sensitivity analyses of compliance with interventions found that even with compliance rates as low as 50%, the screening strategies involving either lifestyle or pharmacological interventions were still cost effective when compared with a strategy of no screening.ConclusionsA policy of a one-off screening for type 2 diabetes and impaired glucose tolerance, with appropriate intervention for those identified with impaired glucose tolerance, seems to be cost effective in an “at risk” population. Changing compliance with screening or interventions or increasing the number of screenings did not change the conclusions of the model.
Given the uncertainty in the results presented here, particularly for the assessment of screening for type 2 diabetes, further research is needed on the long term clinical effects of early diagnosis.



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