Comparison of A1C and Fasting Glucose Criteria to Diagnose Diabetes Among U.S. Adults

OBJECTIVE To compare A1C and fasting glucose for the diagnosis of diabetes among U.S. adults. RESEARCH DESIGN AND METHODS This study included 6,890 adults (> or =20 years of age) from the 1999-2006 National Health and Nutrition Examination Survey without a self-reported history of diabetes who had fasted > or =9 h. A1C > or =6.5% and fasting glucose > or =126 mg/dl were used, separately, to define diabetes. RESULTS Overall, 1.8% of U.S. adults had A1C > or =6.5% and fasting glucose > or =126 mg/dl, 0.5% had A1C > or =6.5% and fasting glucose <126 mg/dl, and 1.8% had A1C <6.5% and fasting glucose > or =126 mg/dl. Compared with individuals with A1C <6.5% and fasting glucose > or =126 mg/dl, individuals with A1C > or =6.5% and fasting glucose <126 mg/dl were younger, more likely to be non-Hispanic black, had lower Hb levels, and had higher C-reactive protein. CONCLUSIONS A1C > or =6.5% demonstrates reasonable agreement with fasting glucose for diagnosing diabetes among U.S. adults.