Hearing impairment has been reported to be one of the late complications of diabetes mellitus (DM), and the frequency varies. Previous data suggest that auditory brainstem potentials deteriorate long before the hearing impairment appears in patients with DM. Delay in neural conductance along the auditory pathway due to DM was assessed by means of auditory brainstem response (ABR) in 43 patients with normal hearing in a controlled study. Patients were classified according to age, presence of neuropathy. metabolic control, and duration and type of DM. ABR recordings revealed that absolute latencies of waves I, III and V were prolonged significantly in the diabetic group when compared to the control group (p < 0.05). When two diabetic groups (insulin-dependent and non-insulin-dependent) were compared with each other, the difference between the latency of wave I and the inter-peak latencies of I-III, III-V and I-V was not significant (p > 0.05). However, the difference between the latencies of waves III and V in the two diabetic groups was statistically significant. The duration of diabetes, blood glucose level and age were not associated with prolonged ABR latencies (p > 0.05). Prolongation of latency of ABR in patients with DM should alert us to possible damage to the auditory nerve, and close follow-up is needed in these patients.