OBJECTIVE -This study examined the relationship between cellular glutathione and vitamin E concentrations and the effect of vitamin E (␣-tocopherol) supplementation on glutathione and lipid peroxidation product concentrations in the erythrocytes of type 1 diabetic patients.RESEARCH DESIGN AND METHODS -We obtained written informed consent to participate in this study from diabetic patients (n = 29) and their age-matched nondiabetic siblings (n = 21) according to the guidelines of the Institutional Review Board on Human Experimentation. Diabetic patients were supplemented with a DL-␣-tocopherol (vitamin E) capsule (100 IU/ orally) or placebo for 3 months in a double-blind clinical trial. Fasting blood samples were collected from each diabetic patient before the start of and after the 3 months of vitamin E or placebo supplementation. Glutathione, malondialdehyde (which is a product of lipid peroxidation), and ␣-tocopherol were determined using high-performance liquid chromatography. A total of 5 diabetic patients were excluded after randomization from the data analyses. Data were analyzed statistically using a paired Student' s t test to compare 12 diabetic patients taking vitamin E with 12 diabetic patients receiving placebo supplementation and to compare diabetic patients with healthy nondiabetic subjects.RESULTS -Erythrocytes of diabetic patients had 21% higher (P Ͻ 0.001) malondialdehyde and 15% lower (P Ͻ 0.05) glutathione concentrations than healthy subjects. Vitamin E in erythrocytes had a significant correlation with the glutathione concentrations in the erythrocytes (r = 0.46, P Ͻ 0.02). Vitamin E supplementation increased glutathione concentrations by 9% (P Ͻ 0.01) and lowered concentrations of malondialdehyde by 23% (P Ͻ 0.001) and of HbA 1c by 16% (P Ͻ 0.02) in erythrocytes of diabetic patients. No differences were evident in these parameters before versus after placebo supplementation.CONCLUSIONS -Glutathione level is significantly related to vitamin E level, and supplementation with vitamin E (100 IU/day) significantly increases glutathione and lowers lipid peroxidation and HbA 1c concentrations in the erythrocytes of type 1 diabetic patients.
This study suggests that modest vitamin E supplementation (100 IU/day) can significantly lower blood GHb and TG levels and does not have any effect on red cell indices in Type I diabetic patients.
Among many factors, elevated lipids and lipid peroxide levels in blood are major risk factors in the development of cardiovascular disease in diabetic patients. This study has examined whether oral supplementation of vitamin E, an antioxidant, has any effect on blood lipid peroxidation products (LP) and lipid profile of diabetic patients. Thirty-five diabetics(D) were supplemented with DL-alpha-tocopherol (E) capsule (orally, 100 IU/d) or placebo (P) for three months in double-blind clinical trials. Plasma E was analyzed by HPLC and LP by the thiobarbituric acid-reactivity; serum lipids by auto-analyzer. Data were analyzed using paired t-test and Wilcoxon Signed Rank Test. Vitamin E supplementation significantly lowered LP and lipid levels in diabetic patients; there were no differences in these parameters after P supplementation. There were no differences in the duration of diabetes and ages of D between P- and E- supplemented groups. This study suggests that vitamin E supplementation significantly lowers blood LP and lipid levels in diabetic patients.
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