Visual evoked potentials in diabetic teen-agers: influence of metabolic control and relationship with peripheral neuropathy.

85 type 1 diabetics aged between 8 and 20 years (mean: 15.06) performed Pattern Reversal Visual Evoked Potentials (PRVEP). In addition all of them were investigated for peripheral neuropathy and 63 subjects for retinopathy. Our study disclosed a subclinical involvement of optic nerve pathways in about 1/4 of diabetic teen-agers. P100 mean latency was delayed in diabetics for both 30' (112.8 +/- 7.7 msec versus 109.1 +/- 4.8 msec) and 15' check size (119.1 +/- 10.5 msec versus 112.8 +/- 5.2 msec). The N75-N140 interpeak latency was also significantly delayed and the mean N75-P100 amplitude was significantly reduced in diabetics. No correlation was found between PRVEPs latency and age, HbA1, and insulin requirement. The mean P100 latency significantly increased with the duration of diabetes. A negative correlation was found at the 30' check size between P100 latency and motor and sensory conduction velocity in all the examined nerves. 10 out of 63 patients, who had been examined with fluorangiography, showed abnormalities; only 2 of these 10 subjects had abnormal PRVEP. The association of prolonged P100 latency, prolonged N75-N140 interpeak latency and reduced N75-P100 amplitude can be considered consequent to a desincronisation of the impulses travelling along the optic pathways.