Chronic vitamin E administration improves brachial reactivity and increases intracellular magnesium concentration in type II diabetic patients

Vascular disease accounts for the majority of the clinical complications in diabetes mellitus. As an exaggerated oxidative stress degree has been post ulated as the link between diabetes mellitus and endothelial function, a po ssible positive effect of plasma vitamin E (Vit.E) administration on brachi al reactivity could be postulated. Our study aims at investigating the poss ible effect of chronic Vit.E administration on brachial reactivity, oxidati ve stress indexes, and intracellular magnesium and calcium content in type II diabetic patients free of diabetic complications. Forty adult, type II d iabetic patients were enrolled in the study, which was deigned as a double blind, randomized vs. placebo trial. At baseline all patients underwent the following tests: 1) anthropometric and metabolic examinations, 2) evaluati on of oxidative stress indexes, 3) intracellular magnesium and calcium meas urements, and 4) determination of arterial compliance and distensibility. T hen, all patients were randomly assigned to Vit.E treatment at a dose of 60 0 mg/day (Evion Forte; n = 20) or placebo (n = 20) over 8 weeks. At the end of this treatment period, a complete reevaluation of the patients was made . Vit.E treatment was associated with a significant improvement in the perc ent change in brachial artery diameter (P < 0.03) and oxidative stress inde xes (P < 0.005). In the Vit.E group, the percent change in brachial artery diameter correlated positively with the percent change in oxidative stress indexes (oxidized/reduced glutathione, Trolox-equivalent antioxidant capaci ty, thiobarbituric acid reaction products, lipid peroxides) and intracellul ar cation content (magnesium and calcium). After adjustment for age, sex, b ody mass index, and wait/hip ratio, all of these correlations remained sign ificant (P < 0.03 for all). Furthermore, adjusting for glycosylated hemoglo bin, plasma total cholesterol, and homeostatic model index, brachial artery diameter was still correlated with the percent change in oxidative stress indexes (P < 0.04 for all). Nevertheless, the relationship between the perc ent change in brachial artery diameter and oxidative stress indexes was no longer significant after adjustment for intracellular Mg and Ca2+. In concl usion, our study demonstrates that chronic administration of Vit.E improves brachial artery reactivity in patients with type II diabetes mellitus. Suc h an effect seems mediated by a reduction in oxidative stress and a regulat ion of intracellular calcium and magnesium contents.