The important role of ascorbic acid is especially relevant in diabetes mellitus where plasma concentrations of ascorbic acid are reduced. This study was conducted to evaluate the effect of ascorbic acid administration on diabetic polyneuropathy. Twenty-two patients having non- insulin de­pendent diabetes mellitus (NIDDM) were included in the study with 10 healthy control subjects of matched age and sex. The patients received SOOmg twice daily of ascorbic acid in addition to their usual antidiabetic therapy, and the study was conduced for three months. Before and after as­corbic acid treatment, the patients were assessed clinically for subjective and objective evidence of neuropathy with neurophysiologica! investigations including nerve conduction velocity
estimation and H reflex latency study. Laboratory investigations included fasting and postprandial serum glu­cose, serum creatinine, liver function tests and serum ascorbic acid deter­minations. The results showed that di­abetic patients had significantly re­duced values of ascorbic acid in comparison to control healthy sub­jects (P<0.05). Ascorbic acid supple­mentation resulted in increased as­corbic acid levels reaching that of control subject (p < 0.05). There was significant reduction of nerve conduc­tion velocity in diabetic patients com­pared to control group(P<0.05). There was non-significant change of nerve conduction velocity after ascorbic acid supplementation. H reflex latency was absent in a group of diabetic subjects having severe polyneuropathy (group A) and was delayed in another group < /p>