Objective: This study examines the association of A1C with cardiovascular disease (CVD) risk factors, coronary artery disease (CAD), and metabolic syndrome in Asian Indians with normal glucose tolerance (NGT).
Research design and methods: This cross-sectional study recruited subjects from phase III of the Chennai Urban Rural Epidemiology Study (CURES), an epidemiological study in a representative population of Chennai (formerly Madras) in South India, conducted between January 2003 and June 2004. Included were 1,644 subjects with NGT, i.e., fasting plasma glucose <100 mg/dl (5.6 mmol/l) and 2-h postload plasma glucose <140 mg/dl (7.8 mmol/l). A1C was measured using the Biorad Variant machine. Metabolic syndrome was defined based on modified Adult Treatment Panel III guidelines.
Results: The mean +/- SD A1C value in the study cohort was 5.5 +/- 0.4%. A1C showed a significant association with BMI (beta = 0.017, P < 0.001), systolic (beta = 0.002, P = 0.028) and diastolic (beta = 0.202, P = 0.017) blood pressure, waist circumference (beta = 0.007, P < 0.001), serum cholesterol (beta = 0.002, P < 0.001), triglycerides (beta = 0.001, P < 0.001), LDL cholesterol (beta = 0.002, P < 0.001), fasting insulin (beta = 0.009, P < 0.001), and homeostasis model assessment of insulin resistance (beta = 0.047, P < 0.001) after adjusting for age and sex. Regression analysis showed that A1C had a strong association with metabolic syndrome that persisted after adjusting for age and sex (odds ratio [OR] 2.9 [95% CI 2.08-4.00]; P < 0.001). A1C also had a strong association with CAD (2.6 [1.23-5.63]; P = 0.01), but the significance was lost when adjusted for age and sex.
Conclusions: There is a strong association of A1C with prevalent CVD risk factors in Asian-Indian subjects with NGT.