Objective: Glycosylated hemoglobin (HbA(1c)) recently has been recommended for the diagnosis of diabetes by the American Diabetes Association, but its value in the prediction of type 2 diabetes is poorly understood. In this study we evaluated how high-normal HbA(1c) levels predict type 2 diabetes.
Research design and methods: We measured HbA(1c) in 919 Caucasian subjects, aged 40-79 years, and recorded new cases of type 2 diabetes in the following 15 years. Diabetes was diagnosed with HbA(1c).
Results: Subjects were stratified according to baseline HbA(1c) (<5.0, 5.00-5.49 [reference], 5.50-5.99, and 6.00-6.49%). Sex- and age-adjusted hazard ratios (95% CI) for type 2 diabetes were 1.11 (0.30-4.41), 1.00, 3.79 (1.79-8.06), and 12.50 (5.51-28.34), respectively. Results did not change after adjusting for several putative confounding factors and were confirmed when models with updated variables were used.
Conclusions: HbA(1c) is an independent risk factor for type 2 diabetes. Subjects with high-normal levels of HbA(1c) deserve particular attention because they have a strong risk of developing diabetes.