Auditory neural function of normal hearing adults with type 2 diabetes mellitus

Abstract

Background: The prevalence of diabetes mellitus is growing worldwide. Type 2 Diabetes Mellitus (T2DM) can lead to damage to various organs by affecting the intricate nerve and blood vessel systems in the body caused by hyperglycaemia, including the auditory neural pathway. Purpose: This study aimed to assess the auditory neural function of adults with T2DM by means of Auditory Brainstem Responses (ABR) with various stimulation rates, presenting with normal behavioural audiometric thresholds. Research Design: Cross-sectional comparative study of ABR latencies and amplitudes and the impact of various stimulation rates in T2DM participants when compared to gender and age-matched controls without diabetes. Study Sample: Sixty participants, thirty with T2DM and 30 without T2DM were recruited and gave informed consent. The thirty T2DM participants aged 20-60 years were recruited from three clinics including two private and one public tertiary clinic. The control group consisted of thirty healthy age and gender-matched volunteers. Behavioural audiometry was performed to ensure a normal pure tone average (< 25 dB HL). Data collection and analysis: The Interacoustics Eclipse Auditory Evoked Potentials (AEP) system was used for the ABR measures which were analysed using linear mixed models. Data consisted of latencies and amplitudes of wave I, III and V and interpeak latencies of I-III, III-V and I-V of the 31.1 Hz rate. Wave V latencies and amplitudes for the 45.1 and 61.1 Hz stimulation rates were also measured. Results: Wave III latency at 31.1 was significantly delayed in those with T2DM compared to the control group (p<0.05). Participants with T2DM presented with prolonged wave V latencies at the faster stimulation rates than those without T2DM, but the shift was not statistically different between groups. Diabetes status had no moderating effect of wave V latency at the different stimulation rates. Conclusion: The results identified that the rate study was not affected by any confounding variables such as diabetes status and glucose level. However, the subclinical neurophysiological pathology, specifically at the level of the brainstem, as demonstrated by the delay in wave III, may be at least part of the reason for complaints relating to bilateral hearing difficulties in noise