A comparison of electrophysiological tests for the early diagnosis of diabetic neuropathy

Clinical criteria and several electrophysiological parameters for detecting nerve damage were compared in 99 patients with diabetes mellitus type 1 an d type 2. Abnormal results were found in sural/radial amplitude ratio (51%) , minimal F-wave latency of the tibial nerve (36.4%), sensory conduction ve locity of the sural nerve (29.8%), and sural sensory nerve action potential amplitude (29.3%) when pooling data from all patients and comparing them t o age- and height-matched normal control subjects. Analysis of all the para meters revealed large differences between the diabetes mellitus type 1 and type 2 groups, suggesting that the type of diabetes must be taken into acco unt when comparing the sensitivity of nerve conduction tests. In diabetes m ellitus type 1, the sural/radial ratio had the dearest correlation with cou rse of illness and was the first parameter to show a significant reduction. We conclude that the simple ratio between sural and radial amplitudes is a very sensitive parameter and abnormalities in this ratio provide the means for earliest detection of neuropathy in diabetes mellitus type 1. (C) 1999 John Wiley & Sons, Inc.