Implications of Alternative Definitions of Prediabetes for Prevalence in U.S. Adults

OBJECTIVE To compare the prevalence of prediabetes using A1C, fasting plasma glucose (FPG), and oral glucose tolerance test (OGTT) criteria, and to examine the degree of agreement between the measures. RESEARCH DESIGN AND METHODS We used the 2005-2008 National Health and Nutrition Examination Surveys to classify 3,627 adults aged ≥ 18 years without diabetes according to their prediabetes status using A1C, FPG, and OGTT. We compared the prevalence of prediabetes according to different measures and used conditional probabilities to examine agreement between measures. RESULTS In 2005-2008, the crude prevalence of prediabetes in adults aged ≥ 18 years was 14.2% for A1C 5.7-6.4% (A1C5.7), 26.2% for FPG 100-125 mg/dL (IFG100), 7.0% for FPG 110-125 mg/dL (IFG110), and 13.7% for OGTT 140-199 mg/dL (IGT). Prediabetes prevalence varied by age, sex, and race/ethnicity, and there was considerable discordance between measures of prediabetes. Among those with IGT, 58.2, 23.4, and 32.3% had IFG100, IFG110, and A1C5.7, respectively, and 67.1% had the combination of either A1C5.7 or IFG100. CONCLUSIONS The prevalence of prediabetes varied by the indicator used to measure risk; there was considerable discordance between indicators and the characteristics of individuals with prediabetes. Programs to prevent diabetes may need to consider issues of equity, resources, need, and efficiency in targeting their efforts.