Effects of alpha-tocopherol supplementation and continuous subcutaneous insulin infusion on oxidative stress in Korean patients with type 2 diabetes

BACKGROUND: Most Koreans with type 2 diabetes are insulin deficient and insulin resistant. Continuous subcutaneous insulin infusion (CSII) provides a suitable amount of insulin to overcome insulin deficiency and achieve near-normal blood glucose concentrations. Our previous study showed, however, that CSII does not reduce oxidative stress even though it normalizes blood glucose concentrations. OBJECTIVE: The purpose of this study was to determine whether CSII plus alpha-tocopherol supplementation for 2 mo would alter oxidative stress in Korean patients with type 2 diabetes. DESIGN: Ninety-eight subjects received CSII plus either 200 mg alpha-tocopherol/d (n = 48) or a placebo (n = 50) for 2 mo. The general characteristics (age, duration of diabetes, body mass index, and blood glucose concentrations) of the 2 groups were not significantly different. RESULTS: Fasting and postprandial blood glucose concentrations of all subjects were normalized after CSII. Fasting plasma insulin concentrations did not differ significantly between the 2 groups after CSII. Lipid peroxide concentrations in plasma and red blood cells decreased and alpha-tocopherol concentrations in plasma and red blood cells increased after alpha-tocopherol supplementation. However, these changes were not affected significantly by CSII. Plasma vitamin C concentrations increased significantly after CSII plus alpha-tocopherol supplementation. However, the activities of antioxidant enzymes in red blood cells did not change significantly after CSII plus alpha-tocopherol supplementation. CONCLUSION: alpha-Tocopherol supplementation was beneficial in decreasing blood lipid peroxide concentrations without altering antioxidant enzyme activities in Korean patients with type 2 diabetes treated with CSII.