Diabetes-related changes in auditory brainstem responses.

OBJECTIVES/HYPOTHESIS: Determine effects on auditory brainstem response (ABR) of diabetes mellitus (DM) severity.

STUDY DESIGN

A cross-sectional study investigating DM severity and ABR in military Veteran subjects with (166) and without (138) DM and with no more than moderate hearing loss.

METHODS

Subjects were classified by three age tertiles (<50, 50-56, and 57+). DM severity was classified as insulin-dependent (IDDM), non-insulin-dependent (NIDDM), or no DM. Other DM measures included serum glucose, HbA1c, and several DM-related complications. ABR measures included wave I, III, and V latencies; I-III, III-V, and I-V latency intervals; and wave V amplitude; for each ear at three repetition rates (11, 51, and 71 clicks/second), and both polarities. Outcomes were stratified by age tertile and adjusted for pure tone threshold at 3 kHz. Repeated measures multivariate analysis of covariance modeled the ABR response at each repetition rate for DM severity (main effect) and hearing at 3 kHz (covariate). Modeled contrasts between ABR variables in subjects with and without DM were examined.

RESULTS

Significant differences existed between no DM and IDDM groups in the younger tertile only. Adjusting for threshold at 3 kHz had minimal effect. Self-reported noise exposure was not related to ABR differences, but HbA1c and poor circulation were.

CONCLUSIONS

IDDM is associated with an increased wave V latency, wave I-V interval, and reduced wave V amplitude among Veterans under 50 years. Results were related to several DM complications.