Effects of long-term supplementation with moderate pharmacologic doses of vitamin E are saturable and reversible in patients with type 1 diabetes

Background: Vitamin E supplementation has been proposed as adjunctive thera py to counteract the increased LDL oxidation in diabetes and thus prevent o r delay cardiovascular complications. Objective: The objective of this study was to investigate the effect of a m oderate pharmacologic dose of vitamin E for less than or equal to1 y in pat ients with type 1 diabetes. Design: The study was double blind and the subjects were randomly assigned to 2 groups: the supplemented group (group S; n = 22) received 250 IU (168 mg) RRR-alpha -tocopherol 3 times/d for 1 y and the placebo group (group P; n = 22) received a placebo for 6 mo followed by 250 IU (168 mg) RRR-alpha -tocopherol 3 times/d for an additional 6 mo. Results: Serum vitamin E doubled after 3 mo of supplementation, from a mean (+/-SD) of 36.9 +/- 10.9 to 66.4 +/- 18.3 mu mol/L (P < 0.0005). Although lipid profiles, glycated hemoglobin, and blood biochemistry values did not change significantly, copper-induced in vitro peroxidizability of LDL and V LDL decreased after 3 mo of supplementation: the production of thiobarbitur ic acid-reactive substances decreased by 30-60% (P < 0.005) and the lag tim e for the appearance of fluorescent products increased from 107 +/- 25 to 1 23 +/- 30 min in group S (P = 0.002 compared with group P). Vitamin E suppl ementation for an additional 3-9 mo resulted in no further changes in serum vitamin E and lipoprotein peroxidizability. Values returned to baseline af ter supplementation ended. Conclusions: Because the improvement in lipoprotein peroxidizability is sat urable and reversible, life-long supplementation with vitamin E should be c onsidered in patients with type 1 diabetes.