Is there a direct correlation between the duration and the treatment of type 2 diabetes mellitus and hearing loss

AIM: The aim of the study was to determine the impact of the duration of diabetes and the control of glycemia on the auditory function of patients with type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS: This prospective study included 80 patients with T2DM (divided depending on when T2DM was diagnosed, and also according to the control of glycemia), and 50 healthy subjects. RESULTS: The hearing threshold in T2DM patients was statistically significantly higher for 1,000 Hz, 2,000 Hz, 4,000 Hz and 8,000 Hz. Absolute latencies of brainstem auditory evoked potentials (BAEP) revealed significant differences between average absolute latencies for waves I, III and V, as well as inter-wave latencies I‒V and I‒III (p <0.001). A statistically significant difference was noted in the presence of transitory otoacoustic emissions (TEOAE) (p <0.001). In T2DM patients with poor glycemic control, where the glycated hemoglobin (HbA1c) is above 7%, the hearing threshold levels were statistically significantly higher in both ears at 8,000 Hz and at 2,000 Hz in the right ear, and the absolute latency of wave V was prolonged in the right ear. There was no evidence that the duration of diabetes significantly affected the auditory threshold, absolute and inter-wave BAEP latencies. CONCLUSION: The patients with T2DM displayed an increased hearing threshold, qualitative changes in BAEP and the absence of TEOAE. The duration of poorly-controlled glycemia had a greater effect on the patients' auditory function than the duration of T2DM. Hippokratia 2016, 20(1): 32-37.