Pharmacologic doses of vitamin E improve insulin action in healthy subjects and non-insulin-dependent diabetic patients

Abstract

Ten control (healthy) subjects and 15 non-insulin-dependent diabetics underwent an oral glucose-tolerance test and a euglycemic hyperinsulinemic glucose clamp before and after vitamin E supplementation (900 mg/d for 4 mo). In control subjects (placebo-treated vs vitamin E-supplemented subjects, respectively) vitamin E reduced the area under the curve for glucose (344 ± 21 vs 287 ± 13 mmol · L⁻¹ · min⁻¹; P < 0.05) and increased total body glucose disposal (39.0 ± 0.3 vs 47.6 ± 0.4 µmol · kg lean body mass⁻¹ · min⁻¹; P < 0.05) and nonoxidative glucose metabolism (23.4 ± 0.2 vs 30.8 ± 0.3 µmol · kg lean body mass⁻¹ · min⁻¹; P < 0.05). In diabetics (placebo-treated vs vitamin E-supplemented subjects, respectively) vitamin E supplementation reduced glucose area under the curve (614 ± 129 vs 544 ± 98 mmol · L⁻¹ · min⁻¹; P < 0.03) and increased glucose disappearance (19.4 ± 0.4 vs 26.4 ± 0.7 µ · kg lean body mass⁻¹ · min⁻¹; P < 0.03), total glucose disposal (19.0 ± 0.7 vs 28.1 ± 0.4 µmol · kg lean body mass⁻¹ · min⁻¹; P < 0.02), and nonoxidative glucose metabolism (8.5 ± 0.3 vs 13.9 ± 0.3 µmol · kg lean body mass⁻¹ · min⁻¹; P < 0.02). Therefore we conclude that administration of pharmacologic doses of vitamin E is a useful tool to reduce oxidative stress and improve insulin action.