Brain stem auditory evoked response (BAER), visual evoked response (VER) and nerve conduction velocities (NCV) were studied in 18 insulin-dependent diabetic children between the ages of 3.5 and 16 years (mean 9.0 ± 3.2 years). The results were compared with those of age-matched controls. The VER latencies of the diabetic children in the right eye and left eye were significantly prolonged when compared with the control group. NCV of n.peroneus and the latency of sensorial n.medianus were significantly impaired when compared with the control group.

Although the latencies of waves III, IV and V of the right ear and the interpeak latencies of I-III, I-V, III-V of both ears were prolonged, the comparison with the control group was not significant. The \beta_2 microglobulin levels of the diabetic patients were significantly higher than those of the control group. There was a positive correlation between the \beta_2 microglobulin and the BAER interpeak latencies of wave III-V in both ears (r: 0.51 p < 0.01). There was also a positive correlation between NCVs of n.peroneus and n.medianus (motor and sensorial) with \beta_2 microglobulin (r: 0.52 p < 0.01) and between VER latencies (r: 0.52 p < 0.01) of both eyes separately.

In our study the prolonged latencies of VER and BAER were detected in the absence of clinical abnormalities in visual and hearing systems. Due to our findings, we conclude that prolongation of latencies of VER and BAER are mostly the first signs of central nervous system (CNS) involvement in insulin-dependent diabetes, and the procedures are easy to perform as well as harmless to patients.

Keywords: brainstem auditory evoked potential, visual evoked potential, HbA1c, β2-microglobulin, insulin dependent diabetes mellitus