It has been reported that diabetic peripheral nerve conducts for several minutes longer than normal nerves during ischemia and retain abnormal preservation of the nerve action potential after 30 minutes on electrophysiological studies.

This study was done to see the effect of the local ischemia on the diabetic peripheral nerves and its usefulness as the earliest diagnostic tool in addition to routine electrophysiological tests of diabetic neuropathy. Median sensory nerve action potential(SNAP) and scalp-recorded somatosensory evoked potential(SSEP) were recorded during and after 30 minutes local ischemia in diabetic patients and in contols.

In control group(n=20), there was the significant increment(34.8%) of latency and the decrement(42.4%) of amplitude of SNAP during 20 minutes ischemia and after 30 minutes SNAP was not evoked in 85% cases(17/20). The increment of latency of SSEP was 14.3% and the decrement of amplitude 29.6%. The SSEP was not evoked in all cases(20/20) during 30 minutes ischemia.

In diabetic group(n=20) the increment of latency and the decrement of amplitude of SNAP were 19.2% and 13.6%, respectively, and those of SSEP were 3.7% and 9.2% respectively; it was significantly less changes than in controls during ischemia(p<0.05), and there was no one case that SNAP and SSEP were not evoked on 30 minutes ischemia.