Elevated Hemoglobin A_1c (HbA_1c) in Adults without a History of Diabetes in the U.S.

Abstract

Objective: to examine the prevalence and correlates of elevated HbA_1c in a large, nationally representative sample of adults without diabetes in the United States.

Research Design and Methods: we analyzed data from 15,934 participants without diagnosed diabetes aged 20 and older who had HbA1c measurements in the 1999-2006 National Health and Nutrition Examination Survey (NHANES), a cross-sectional and nationally representative sample of the U.S. population.

Results: The overall prevalence of HbA1c >6% was 3.8% corresponding to 7.1 million adults in the U.S. population. Approximately 90% of these individuals had fasting glucose ≥ 100 mg/dl. Older age, male gender, non-Hispanic black race/ethnicity, hypercholesterolemia, higher body mass index, and lower attained education were significantly associated with having a higher HbA1c level even among individuals with normal fasting glucose (<100 mg/dl) and after multivariable adjustment.

Conclusions: A single elevated HbA1c level (HbA1c >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. Non-diabetic adults with elevated HbA1c are likely to have impaired fasting glucose and an array of other risk factors for type 2 diabetes and cardiovascular disease.