Comparison of A1C and Fasting Glucose Criteria to Diagnose Diabetes Among US 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 (>= 20 years of age) from the 1999-2006 National Health and Nutrition Examination Survey without a self-reported history of diabetes who had fasted >= 9 h. A1C >= 6.5% and fasting glucose >= 126 mg/dl were used, separately, to define diabetes. RESULTS - Overall, 1.8% of U.S. adults had A1C >= 6.5% and fasting glucose >= 126 mg/dl, 0.5% had A1C >= 6-5% and fasting glucose <126 mg/dl, and 1.8% had A1C <6.5% and fasting glucose >= 126 mg/dl. Compared with individuals with A1C <6.5% and fasting glucose >= 126 mg/dl, individuals With A1C >= 6.5% and fasting glucose <1.26 mg/dl were younger, more likely to be non-Hispanic black, had lower Hb levels, and had higher C-reactive protein. CONCLUSIONS - A1C >= 6.5% demonstrates reasonable agreement with fasting glucose for diagnosing diabetes among U.S. adults.