Degree of Hearing Threshold in Patients with Type 2 Diabetes Mellitus

Abstract

Background: Type 2 diabetes mellitus (T2DM) leads to multiple chronic complications in the body including sensory functions. Aim: The aim of this study was to determine the hearing threshold in middle-aged patients with T2DM and categorize it according to the presence or absence of hearing loss. Materials and Methods: A prospective, cross-sectional study was performed with 40 patients with T2DM (mean age 58 ± 8.6 years and mean time of T2DM evolution 11.9 ± 8.2 years) and 40 nondiabetic subjects (mean age of 52.4 ± 10.9 years). Pure tone audiometry was performed with a Grason-Stadler GSI 18 screening audiometer, 11 frequencies (0.125–8 kHz) were evaluated and classified as low, medium, and high. Hearing loss was defined as a hearing threshold >20 decibels (dB) and was classified as: mild: 21–40 dB, moderate: 41–70 dB, severe: 71–90 dB, and profound: > 90 dB. Results: Compared to the control group, diabetic patients presented a significant increase in the hearing threshold at medium (P < 0.05) and high (P < 0.0001) audiometric frequencies. When hearing loss was present, it was almost entirely mild (>80%) in the control group, whereas diabetic patients presented moderate, severe, and even profound levels of hearing loss. A linear correlation was found between the diagnosis time of T2DM and the degree of hearing loss at high frequencies (P = 0.04) as well as at medium frequencies (P = 0.01). Conclusions: T2DM affects hearing from the early stages of the disease; routine evaluation of hearing function should be considered in this population.