Endothelial function, insulin action and cardiovascular risk factors in young healthy adult offspring of parents with Type 2 diabetes: effect of vitamin E in a randomized double‐blind, controlled clinical trial

Abstract

Background and aims Endothelial dysfunction, insulin resistance and oxidative stress are believed to be central and associated mechanisms in atherogenesis. We aimed to determine the effect of the antioxidant vitamin E on endothelial function, insulin action and cardiovascular risk markers in young healthy adult offspring of parents with Type 2 diabetes. Methods Healthy, glucose‐tolerant adults (18–38 years), 14 (12 male/2 female) with at least one parent with Type 2 diabetes, and 14 (12 male/2 female) subjects with no family history of diabetes (controls) were studied. Insulin action was assessed by euglycaemic hyperinsulinaemic clamp (1 mU/kg/min). Endothelial function was assessed by forearm blood flow (FBF) responses to intra‐brachial artery infusions of acetylcholine (ACh) (endothelium‐dependent vasodilation), sodium nitroprusside (SNP) (endothelium‐independent vasodilation) and N^G‐monomethyl l‐arginine (LNMMA) (nitric oxide synthase inhibition). Thirteen offspring (18–38 years, 11 male/2 female, BMI < 30 kg/m²) completed a randomized, double‐blind, crossover trial (12 weeks vitamin E 800 IU/day or placebo, 6‐week washout). Results Exogenous glucose infusion rates to maintain euglycaemia were positively associated with response to acetylcholine in offspring (r = 0.61, P < 0.05), and were linked with triglycerides. Vitamin E had no effect on endothelial function, insulin action or cardiovascular risk markers in healthy adult offspring of parents with Type 2 diabetes. Conclusions Our results support a positive association between insulin action and endothelial‐dependent vasodilation in young healthy adult offspring of parents with Type 2 diabetes, but indicate no effect of vitamin E on these parameters.