Visual evoked potentials in diabetes mellitus.

25 diabetic patients have been studied in order to investigate the possible effects of the disease on the central nervous system by means of pattern shift visual evoked potentials. Patients with diabetic retinopathy, glaucoma and cataract were excluded from the study. Results obtained from a control group of 30 normal subjects were compared to those of the patient group in which sural nerve conduction velocities have also been determined to see whether there is a correlation between peripheral and central involvement of the nervous system. In diabetic patients latency prolongation in the P100 and N140 components were observed. The N90-N140 interpeak latency was also prolonged. In addition, in patients with longstanding diabetes mellitus the incidence of VEP abnormalities was found to be high. Pathologic changes in VEP latencies did not show any correlation with sural nerve conduction abnormalities.