Somatosensory and visual evoked potentials study in young insulin-dependent diabetic patients

To evaluate central nervous system involvement in diabetes, somatosensory (SEPs) and visual (VEPs) evoked potentials were investigated in a group of 35 patients and 20 sex, age-matched controls. In order to avoid methodological biases due to different type and duration of disease, we studied an omogeneous group of young insulin-dependent diabetics with ten or more year duration of disease. In our results VEP and SEP parameters were found abnormal in 10 (28%) patients, all of whom presenting clear signs of peripheral neuropathy. In diabetic patients median and tibial SEPs showed significant increase in absolute latency mean values of several components except interpeak intervals, as well as mean P 100 latencies were significantly increased in both eyes at 15' check size stimulation pattern. VEP and SEP components were not generally significantly associated with the indices of peripheral function. In contrast, in diabetics significant correlations were found between P 100 latencies and median SEP parameters including interpeak intervals. No major associations related VEP and SEP latencies to duration of diabetes and prevailing glycaemic control. In conclusion the central nervous system involvement in young insulin-dependent diabetics, even though diffusely present, seems unequivocally concomitant to peripheral conduction impairment.