Antioxidants and coronary artery disease among individuals with type 1 diabetes: Findings from the Pittsburgh Epidemiology of Diabetes Complications Study

Objective: Oxidative stress has been implicated in the development of diabetes and cardiovascular disease. We evaluated the effect of serum antioxidants and total antioxidant reserve (TAR) on coronary artery disease (CAD) incidence in type I diabetes. Methods: Subjects were identified from the Pittsburgh Epidemiology of Diabetes Complications Study (EDC) cohort, a 10-year prospective study of childhood-onset type I diabetes. Mean age at baseline was 28 and diabetes duration 19 years. Coronary artery disease was defined as physician-diagnosed angina, confirmed MI, stenosis >= 50%, ischemic electrocardiogram (ECG), or revascularization. Controls were gender, age, and diabetes duration (+/- 3 years) matched with cases. Samples and risk factors used in analyses were identified from the earliest exam prior to incidence in cases (54 cases, 67 controls). Results: None of the antioxidant measures (alpha-tocopherol, gamma-tocopherol, retinol, TAR) showed protection against incident CAD overall. However, a protective effect of alpha-tocopherol against CAD was observed among antioxidant supplement users (HR=0.22, 95% CI=0.10-0.49) and in renal disease (HR=0.46, 95% CI=0.23-0.91). Despite similar U-tocopherol concentration, there was no protective effect among nonusers of antioxidant supplements. Conclusions: High a-tocopherol levels among patients with renal disease and in those using vitamin supplements were associated with lower CAD risk in type I diabetes. The specificity of these effects merits further investigation. (c) 2006 Elsevier Inc. All rights reserved.