Potential Mediators of Diabetes-Related Hearing Impairment in the U.S. Population

OBJECTIVE We examined potential mediators of the reported association between diabetes and hearing impairment. RESEARCH DESIGN AND METHODS Data come from 1,508 participants, aged 40-69 years, who completed audiometric testing during 1999-2004 in the National Health and Nutrition Examination Survey (NHANES). We defined hearing impairment as the pure-tone average >25 decibels hearing level of pure-tone thresholds at low/mid (500, 1,000, and 2,000 Hz) and high (3,000, 4,000, 6,000, and 8,000 Hz) frequencies. Using logistic regression, we examined whether controlling for vascular or neuropathic conditions, cardiovascular risk factors, glycemia, or inflammation diminished the association between diabetes and hearing impairment. RESULTS Diabetes was associated with a 100% increased odds of low/mid-frequency hearing impairment (odds ratio 2.03 [95% CI 1.32-3.10]) and a 67% increased odds of high-frequency hearing impairment (1.67 [1.14-2.44]) in preliminary models after controlling for age, sex, race/ethnicity, education, smoking, and occupational noise exposure. Adjusting for peripheral neuropathy attenuated the association with low/mid-frequency hearing impairment (1.70 [1.02-2.82]). Adjusting for albuminuria and C-reactive protein attenuated the association with high-frequency hearing impairment (1.54 [1.02-2.32] and 1.50 [1.01-2.23], respectively). Diabetes was not associated with high-frequency hearing impairment after controlling for A1C (1.09 [0.60-1.99]) but remained associated with low/mid-frequency impairment. We found no evidence suggesting that our observed relationship between diabetes and hearing impairment is due to hypertension or dyslipidemia. CONCLUSIONS Mechanisms related to neuropathic or microvascular factors, inflammation, or hyperglycemia may be mediating the association of diabetes and hearing impairment.