Early indices of reduced cochlear function in young adults with type-1 diabetes revealed by DpOAE fine structure

Abstract

Background: The relationship between type-1 diabetes mellitus (DM) and cochlear dysfunction remains inconclusive. Purpose: The purpose of this study was to examine otoacoustic emissions (OAEs) in normal-hearing young adults with type-1 DM as compared with matched controls and identify potential covariates influencing OAE findings. Research Design: Cross-sectional study. Study Sample: N 5 40 young adults aged 18–28 years including individuals with type-1 DM (n 5 20) and age–gender matched controls (n 5 20) with normal hearing sensitivity. Data Collection and Analysis: Measures of pure-tone threshold sensitivity and OAEs, including distortion product otoacoustic emissions (DPOAEs), transient evoked OAEs, and DPOAE fine structure, were compared between groups. Covariates such as noise exposure and DM-related factors (e.g., duration of disease, glycated hemoglobin levels) were considered. Statistical analysis included analysis of variance and linear regression. Results: Measures of hearing sensitivity and auditory function in both groups were comparable for all assays, except DPOAE fine structure. A reduced number of fine structure peaks and component amplitudes were found in the type-1 diabetes DM group with the primary difference in the reflection component. Conclusions: The results indicate that reduced cochlear function in young adults with type-1 DM can be revealed using DPOAE fine structure, suggesting potential clinical applications of DPOAE fine structure in early identification of cochlear pathology. Potential factors underlying these findings are discussed.