Context: Recently, several studies have investigated the relationship between diabetes and hearing impairment, but results were inconsistent.
Objective: Our objective was to compare the prevalence of hearing impairment between diabetic and nondiabetic adults.
Data sources: We performed a systematic literature search using MEDLINE (1950 to May 30, 2011) and EMBASE (1974 to May 30, 2011).
Study selection: Cross-sectional studies were included if data on numbers of hearing-impaired and non-hearing-impaired cases with diabetes were presented. Hearing impairment was limited to that assessed by pure-tone audiometry that included at least 2 kHz of frequency range and was defined as progressive, chronic, sensorineural, or without specified cause.
Data extraction: Two authors independently extracted relevant data. Odd ratios (ORs) of hearing impairment related to diabetes calculated in each study were pooled with the random-effects model.
Data synthesis: Data were obtained from 13 eligible studies (20,194 participants and 7,377 cases). Overall pooled OR (95% confidence interval) of hearing impairment for diabetic participants compared with nondiabetic participants was 2.15 (1.72-2.68). OR was higher in younger participants (mean age, ≤60 yr) than in those over 60 yr among which the OR remained significant (2.61 and 1.58, P = 0.008). The strength of the association between diabetes and prevalence of hearing impairment was not significantly influenced by whether participants were matched for age and gender (P = 0.68) or whether participants chronically exposed to noisy environments were excluded (P = 0.19).
Conclusions: Current meta-analysis suggests that the higher prevalence of hearing impairment in diabetic patients compared with nondiabetic patients was consistent regardless of age.