Diabetic neuropathy: A clinical, laboratory and electrodiagnostic study

The objective of this study was to determine the relationship between nerve conduction velocity (NCV) and hyperglycemia and to assess the extent of NCV changes in adult-onset diabetic patients before and after diabetic treatment. Twenty-five diabetic males (mean age = 50.9 years) were tested twice prior to beginning diabetic treatment. Eighteen of these 25 were also tested at 1, 3, 6, and 12 months after initiation of therapy. Both groups were compared to 23 age-matched controls. Each test session consisted of NCV and clinical sensory and blood chemistry testing. The findings revealed that, before treatment, average NCVs of the median, peroneal, sural, and tibial nerves and H-reflex latency results were all significantly impaired in diabetic subjects (p<0.025). No difference was found between right and left NCVs of the same nerve (p<0.05) and NCVs in the lower as well as the upper extremities were significantly reduced (p<0.05). Thus, it appears that the neuropathy in these patients was symmetrical and diffuse. Peroneal and median motor nerves showed the greatest amount of NCV slowing when compared to normal values. Furthermore, median, peroneal, and tibial motor NCVs and H-reflex latencies correlated significantly with the degree of hyperglycemia in diabetic subjects before treatment. After initiation of diabetic treatment, median motor NCVs after 1, 3, 6 and 12 months showed significant improvement when compared to baseline NCV values (all p<0.05). Also, the improvement in median NCVs after 3 and 12 months and peroneal NCV after 3 months directly correlated to decreased fasting plasma glucose levels (p<0.05).