Assessment of Cochlear Function Using DPOAE Fine Structure in Individuals with Type 2 Diabetes Mellitus

Abstract

The present study aimed to evaluate cochlear outer hair cells function in individuals with Type 2 Diabetes Mellitus (T2DM) and compared with individuals without T2DM using DPOAE fine structure. A total of 60 participants were recruited and divided into four groups [Middle-aged adults with T2DM (40-50 years); Middle aged adults without T2DM (40-50 years); older adults with T2DM (60-70 years) & Older adults without T2DM (60-70 years)]. The DPOAE fine structure were measured across frequencies from 500 Hz to 4000 Hz, following a fine structure protocol of 32 points per octaves. The collected data were tabulated and analysed using SPSS Version 26. Shiparo-Wilk test was done to check the normal distribution of the data. Since, data was not normally distributed, non-parametric test was done. Mann-Whitney U test was done to compare between clinical and control groups i.e. Middle aged adults with and without T2DM; older adults with and without T2DM. The results showed statistically significant differences between middle aged adults with and without T2DM for DPOAE fine structure between frequencies 4000 Hz to 1000 Hz. Whereas in older adults, the DPOAE fine structure were statistically significant different between with and without T2DM for frequencies between 4000 Hz to 2000 Hz only. Overall, there were reduction in the amplitude (SNR) among individuals with T2DM in comparison to the without T2DM for both middle-aged adults as well as older adults. Further, there were no significant differences observed for number of ripples in each group across frequencies between 4000 Hz to 1000 Hz. The spacing of the ripples was lower (reduced) across frequencies from 4000 Hz to 1000 Hz in middle-aged T2DM and older adults with T2DM. in addition, there were no significant difference observed for the depth of the ripples across frequencies (4000 Hz to 1000 Hz) between clinical and control groups. These above results indicate that among individuals with T2DM, DPOAE fine structure indicates the early sign of outer hair cell dysfunctions in comparison to the healthy middle-aged and older adults. The study emphasizes that the DPOAE fine structure is a valuable and non-invasive tool for early detection of cochlear issues in diabetic’s population, even before they show obvious signs of hearing impairment. However, further research with larger sample sizes and a wider range of frequencies would confirm these finding and improve early identification of cochlear function in individuals with T2DM.