Daily Vitamin E Supplements Improve Metabolic Control But Not Insulin Secretion in Elderly Type II Diabetic Patients

OBJECTIVE To investigate the potential metabolic benefits deriving from daily vitamin E administration in type II diabetic patients.

RESEARCH DESIGN AND METHODS Twenty-five type II diabetic patients were invited to randomly take placebo or vitamin E (d-α-tocopherol; 900 mg/day) along a similar 3-mo period in a double-blind, crossover procedure. A wash-out period of 30 days separated the two treatment periods. At the end of each treatment period blood samples were drawn for plasma metabolites determination, and an intravenous glucose tolerance test (25 g of glucose as bolus in 3 min) was performed. During this study oral hypoglycemic agents were not discontinued or changed in their dosage.

RESULTS Chronic vitamin E administration reduced plasma glucose (8.3 ± 0.3 vs. 7.5 ± 0.2 mM, P > 0.05), triglycerides (2.27 ± 0.08 vs. 1.67 ± 0.09 mM, P < 0.02), free fatty acids (786 ± 116 vs. 483 ± 64 mM), total cholesterol (6.74 ± 0.09 vs. 5.50 ± 0.10 mM, P < 0.05), low-density lipoprotein cholesterol (4.73 ± 0.11 vs. 3.67 ± 0.07 mM, P < 0.04), and apoprotein B (1.7 ± 0.3 vs. 1.0 ± 0.1 g/L) levels but did not affect β-cell response to glucose. HbA₁ levels (7.8 ± 0.3 vs. 7.1 ± 0.5%, P < 0.05) were also significantly lowered after chronic vitamin E administration.

CONCLUSIONS Daily vitamin E supplements seem to produce a minimal but significant improvement in the metabolic control in type II diabetic patients. More studies are necessary before conclusions can be drawn about the safety of vitamin E during long-term administration.