Pharmacological doses of vitamin E and insulin action in elderly subjects

Twenty elderly (77 +/- 0.4 y), nonobese [body mass index (in kg/m2) 26.4 +/- 0.5] subjects with normal glucose tolerance were submitted to a euglycemic hyperinsulinemic (3.5 pmol.min/kg) glucose clamp in a double-blind, crossover, randomized procedure after 4 mo treatment with either vitamin E (900 mg d-alpha-tocopherol/d, Ephynal; Roche, Milan, Italy) or placebo. Body mass index was practically unchanged throughout the study. After the glucose clamp, insulin-mediated stimulation 2 of whole-body glucose disposal (18.4 +/- 0.5 vs 26.1 +/- 0.6 mumol.min/kg lean body mass P < 0.02) was significantly potentiated by vitamin E rather than placebo administration. Furthermore, net changes in plasma vitamin E concentrations correlated with net changes in insulin-stimulated whole-body glucose disposal (r = 0.60 P < 0.003). Plasma vitamin E concentrations seem to play an important role in the modulation of insulin action in elderly people.