Independent Association of HbA1c and Incident Cardiovascular Disease in People Without Diabetes

Recent studies have reported no association between elevated glycated hemoglobin (HbA(1c)) and incident cardiovascular disease (CVD) among women without diabetes. This study describes associations between HbA(1c) and new onset CVD in a representative adult population cohort. Assessment of participants in The North West Adelaide Health Study (NWAHS), a population study of randomly selected adults (age >= 18 years, n = 4,060), included measurement of height, weight, blood pressure, fasting lipids, glucose, and HbA(1c). A self-completed questionnaire assessed doctor-diagnosed diabetes, CVD and stroke, smoking status, and demographics. The cohort was followed for an average 3.5 years. Of the 2,913 adults free of diabetes at baseline and follow-up, 94 (3.5%) reported new onset coronary heart disease (CHD) and/or stroke. Compared with those with an HbA(1c) <= 5.0%, risk of new onset CVD was increased in those with HbA(1c) 5.4-5.6% (odds ratio (OR) 2.5, 95% confidence interval (CI) 1.4, 4.6), and >= 5.7% (OR 1.9, 95% CI 1.1, 3.4), after adjustment for other risk factors. The association was stronger in women than men (P = 0.03), and attenuated to only a small degree by addition of impaired fasting glucose (IFG), hypertension, hypercholesterolemia, BMI, waist circumference, or smoking to the model. Elevated HbA(1c) is related to new onset CVD over a relatively short follow-up period in both men and women without diabetes and who do not develop diabetes, after adjustment for other major risk factors. Unlike previous studies, this relationship was not substantially attenuated by other traditional risk factors.