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

Abstract

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. 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. 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. 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. 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.