Auditory brainstem evoked potentials in insulin-dependent diabetics with and without peripheral neuropathy.

Auditory Brainstem Evoked Potentials (ABEP) were recorded from 33 insulin-dependent diabetes mellitus (IDDM) patients (17 with diabetic peripheral neuropathy and 16 without) as well as from 20 normals. Pure-tone audiometry, speech reception threshold and discrimination were also evaluated. Sub-clinical pure-tone threshold elevation was observed for IDDM patients with neuropathy. Pure-tone thresholds of IDDM patients without neuropathy were not significantly different from those of normals. ABEP abnormality (at 10/sec click rate) was observed in 31% of IDDM patients with neuropathy, rising to 44% when 55/sec click rate measures were included. Abnormalities included bilateral and symmetrical peak-latency prolongations for all waves, greater for the later waves, and prolongation of V-I and V-III interpeak latency differences, all at 10/sec, and only prolonged peak latency for I at increased rate. Abnormalities coincided with microangiopathy and peripheral neuropathy. The incidence of ABEP abnormality for IDDM patients without neuropathy was only 12%, unilateral and sporadic in nature. As a group, IDDM patients with neuropathy had significantly prolonged IV and V peak-latencies, compared with the normals, or with the IDDM patients without peripheral neuropathy. In contrast, IDDM patients without neuropathy resembled the normals in all respects. ABEP have proven useful in understanding the variety of pathologies underlying the clinical manifestation of diabetes.