Trends in A1C Concentrations Among U.S. Adults With Diagnosed Diabetes From 1999 to 2004
- Earl S. Ford, MD, MPH1,
- Chaoyang Li, MD, PHD1,
- Randie R. Little, PHD2 and
- Ali H. Mokdad, PHD1
- 1Division of Adult and Community Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia
- 2Departments of Pathology, Anatomical Sciences, and Child Health, University of Missouri School of Medicine, Columbia, Missouri
- Address correspondence and reprint requests to Earl Ford, MD, MPH, Centers for Disease Control and Prevention, 4770 Buford Highway, MS K66, Atlanta, GA 30341. E-mail: eford{at}cdc.gov
A1C is formed when glucose reacts nonenzymatically with amino acids on hemoglobin. Its concentration represents an integrated measure of glucose concentration during hemoglobin's lifespan, which is about 2–3 months (1). Because A1C concentration predicts the risk for microvascular and macrovascular complications (2,3), it is used in the clinical setting to assess longer-term glycemic control among people with diabetes. Generally, A1C concentrations <7% are regarded as acceptable glycemic control (4).
Approximately 44% of U.S. adults with diagnosed diabetes had a concentration of A1C <7% during 1988–1994 compared with ∼36–37.0% during 1999–2000 (5,6). More recently, data from the National Committee for Quality Assurance showed steady increases in the percentage of patients receiving annual testing for A1C and decreases in the percentage of patients with poor glycemic control from 2000 to 2006 (7). Our objective was to examine trends in glycemic control among U.S. adults with diagnosed diabetes from 1999 to 2004.
RESEARCH DESIGN AND METHODS—
The National Health and Nutrition Examination Survey (NHANES) 1999–2004 included nationally representative samples of the noninstitutionalized, civilian U.S. population, selected using a multistage, stratified sampling design (8). Participants were asked the following: “Other than during pregnancy, have you ever been told by a doctor or health professional that you have diabetes or sugar …
