Objective: The present study has examined the effect of vitamin E, the principal modulator of free radical activity, on electrophysiological parameters in patients with diabetic peripheral sensorimotor polyneuropathy, matched for duration of disease and metabolic control.
Research design and methods: A total of 21 subjects with type 2 diabetes were enrolled in this double-blind randomized placebo-controlled study (vitamin E, 11 patients; placebo, 10 patients). Patients were randomly assigned to receive either 900 mg vitamin E or placebo for 6 months. The average dietary vitamin E consumption of the subjects was similar during the study. The main outcome measure was the electrophysiological tests assessing nerve conduction. Fasting plasma glucose, HbA1, postprandial plasma glucose, and electrophysiological parameters in the basal state and after 6 months of treatment were studied.
Results: Glycemic indexes did not show any significant changes during the study, whereas nerve conduction improved significantly in 2 of the 12 studied electrophysiological parameters after 6 months in patients on vitamin E supplementation. The changes in the electrophysiological parameters were obvious in the median motor nerve fibers and tibial motor nerve fibers. Nerve conduction velocity in the median motor nerve fibers (P = 0.0019) and tibial motor nerve distal latency (P = 0.0284) improved significantly after 6 months of vitamin E supplementation.
Conclusions: This study shows that defective nerve conduction in diabetic subjects with mild-to-moderate peripheral neuropathy may be improved by pharmacological doses of vitamin E supplementation. Further studies with a larger number of patients for longer periods of time are needed.