3Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
RESEARCH DESIGN AND METHODS- We analyzed data from 15,934 participants aged 20 years without diagnosed diabetes who had A1C measurements in the 1999?2006 National Health and Nutrition Examination Survey, a cross-sectional and nationally representative sample of the U.S. CONCLUSIONS- A single elevated A1C level (A1C >6%) is common in the general population of adults without a history of diabetes and is highly reliable for the detection of elevated fasting glucose. A1C is an integrated measure of circulating glucose levels and tracks well in individuals over time. NHANES is an ongoing cross-sectional, multistage, stratified, clustered probability sample of the U.S. A1C measurements for NHANES 1999?2004 were performed by the Diabetes Diagnostic Laboratory at the University of Missouri-Columbia using Primus CLC330 and Primus CLC 385 instruments (Primus, Kansas City, MO). For the purposes of this study, we defined "elevated A1C" as A1C >6% in this population without a history of diabetes. Estimates from this study are nationally representative of the noninstitutionalized population of adults 20 years in the U.S.
This analysis suggests that elevated A1C (>6%) is common in the general population of nondiabetic adults. Significant advantages of adopting A1C for the screening and diagnosis of diabetes are the high repeatability of the measurement (17,18) and the high specificity of elevated values for detecting undiagnosed diabetes (19?21). It is unclear why nondiabetic non-Hispanic blacks have consistently higher A1C values even in the setting of normal fasting glucose levels and after adjustment for demographic and clinical characteristics.
This study has several strengths including the large, nationally representative sample of healthy, nondiabetic individuals. To date, the diagnostic utility of A1C has largely been assessed by its accuracy (as measured by its sensitivity and specificity) to detect glucose-defined cases of diabetes (25). Normal blood sugar levels chart for adults, This simple chart shows target blood sugar levels for before and after meals, after fasting, before exercise, and at bedtime, as well as an a1c target.. Blood sugar – wikipedia, the free encyclopedia, The blood sugar concentration or blood glucose level is the amount of glucose (sugar) present in the blood of a human or animal. Fast food is the term given to food that can be prepared and served very quickly, first popularized in the 1950s in the United States.


A1C measurements in NHANES 2005?2006 were performed by the Diabetes Laboratory at the University of Minnesota using a Tosoh A1c 2.2 Plus Glycohemoglobin Analyzer (Tosoh Medics, San Francisco, CA).
SEs for all estimates were obtained using the Taylor series (linearization) method following NCHS-recommended procedures (16). Recent recommendations have stated that diagnosis based on A1C should be confirmed using a glucose-dependent test (FPG or OGTT) or by a second A1C (11). We benefited from the rigorous measurement of risk factors using standardized protocols and strict quality control data collection and laboratory procedures in NHANES. Please download the latest version of the Google Chrome, Mozilla Firefox, Apple Safari, or Windows Internet Explorer browser.
Analyses of FPG categories were limited to the morning plasma glucose sample and corresponding 8-year fasting subsample weights were used for these analyses. Adjusted odds ratios (ORs) and their corresponding 95% CIs were estimated from logistic regression models to assess the association between potential risk factors and elevated A1C levels. Census to obtain estimates of the number of nondiabetic individuals with elevated A1C in the U.S. Mean A1C level and the proportion of individuals with A1C >6% increased considerably with age. We next examined the same variables but limited the population to individuals with normal A1C (A1C 5.2%) (Table 2). Important limitations include the cross-sectional design, which limits our conclusions regarding the temporality of the observed associations. Thus, it seems reasonable to adopt a single elevated A1C value as being diagnostic for diabetes. For the present study, we excluded those individuals who reported that a doctor or health care profession had ever told them they had diabetes (n = 1,900), who were missing information on diabetes status (n = 288), or who were missing A1C data (n = 986).
Our analyses of fasting glucose were limited to the fasting subpopulation of adults without diabetes who were not missing A1C data (n = 7,772).
All A1C measurements were standardized to the reference method used for the Diabetes Control and Complications Trial.
We conducted multivariable logistic analyses modeling A1C >6% as the outcome in the overall population.


Requiring confirmation of a highly reliable test by one that is less reliable poses problems for the interpretation of any discrepancy between the two values. However, the real test of utility for A1C as a screening or diagnostic test of diabetes is its association with long-term clinical outcomes in an initially nondiabetic population specifically in comparison with fasting glucose levels. Elevated A1C levels were particularly common among older adults, non-Hispanic blacks, and obese individuals.
The American Diabetes Association recommends repeating an elevated fasting glucose measurement to confirm the diagnosis of diabetes (13). To address this question we need large, observational studies of A1C in populations of individuals without diabetes. Current smoking was associated with higher A1C and current alcohol consumption with lower A1C in this population with normal glucose levels. There is little marginal gain to repeating the A1C test within a short (several week) time period.
The use of a single measurement of fasting glucose rather than two will overestimate the prevalence of undiagnosed diabetes (17). A history of cardiovascular disease was defined on the basis of a self-reported history of coronary heart disease, angina, previous heart attack, or stroke.
Model 2 included all variables in model 1 plus hypertension, hypercholesterolemia, BMI, education, history of cardiovascular disease, alcohol consumption, and C-reactive protein categories. Nonetheless, interpretation of single measurements of fasting glucose and A1C as analyzed in this study reflects a common clinical decision-making setting.
Although we cannot rule out the possibility of laboratory differences over time, calibration of A1C to account for the change in laboratories in 2005?2006 using a published equation (14) did not appreciably alter our results. The lack of OGTT data in the fasting glucose subsample for all survey years is an important limitation of this study.



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Comments

  1. 08.01.2015 at 15:48:40


    Blood sugar at age 45 would go on to develop diabetes, and half of those cause increased blood sugar readings.

    Author: A_ZER_GER
  2. 08.01.2015 at 14:36:24


    Urine or obtain a drop of blood from the finger to check the blood endocrinologist.

    Author: L_E_O_N