Original Article: Complications Relationship of Type 2 diabetes to the prevalence, incidence and progression of age-related hearing loss

Aims Type 2 diabetes and associated microvascular abnormalities are postulated to affect hearing. Our study reports on the relationship between Type 2 diabetes and the prevalence, 5-year incidence and progression of hearing impairment in a representative, older, Australian population. Methods The Blue Mountains Hearing Study is a population-based survey of age-related hearing loss conducted in a defined suburban area, west of Sydney. Hearing loss was defined as the pure-tone average of frequencies 0.5, 1.0, 2.0 and 4.0 kHz > 25 decibels hearing level (dB HL) in the better ear (bilateral hearing loss). Type 2 diabetes was defined from reported physician-diagnosed diabetes or fasting blood glucose ‡ 7.0 mmol ⁄l. Results Age-related hearing loss was present in 50.0% of diabetic participants (n = 210) compared with 38.2% of nondiabeticparticipants(n = 1648),oddsratio(OR)1.55[95%confidenceinterval(CI)1.11‐2.17],afteradjustingformultiplerisk factors. A relationship of diabetes duration with hearing loss was also demonstrated. After 5 years, incident hearing loss occurred in18.7%of participants with, and 18.0% of those withoutdiabetes, adjusted OR 1.01(CI0.54‐1.91).Progression of existing hearing loss (> 5 dB HL), however, was significantly greater in participants with newly diagnosed diabetes (69.6%) than in those without diabetes (47.8%) over this period, adjusted OR 2.71 (CI 1.07‐6.86). Conclusions Type 2diabeteswasassociatedwithprevalent,butnotincidenthearinglossinthisolderpopulation.Accelerated hearing loss progression over 5 years was more than doubled in persons newly diagnosed with diabetes. These data explore further reported links between Type 2 diabetes and age-related hearing loss.