Diabetes' association with hearing loss examined in meta-analysis

Diabetic patients have more hearing impairments than nondiabetic patients at all ages, a meta-analysis concluded.

Researchers conducted a meta-analysis of 13 cross-sectional studies (only one prospective study had been conducted, the authors noted) that involved more than 20,000 patients. The studies, conducted in countries around the world, assessed hearing impairments by pure-tone audiometry that included at least 2 kHz of frequency range. Hearing impairment was defined as progressive, chronic, sensorineural, or without a specified cause. Results appeared online on Nov. 12 in the Journal of Clinical Endocrinology and Metabolism.

There was an overall pooled odds ratio (OR) of 2.15 (95% CI, 1.72 to 2.68) of hearing impairment for diabetic patients compared with nondiabetic ones. The increase in risk associated with diabetes was greater in younger patients (≤60 years old) compared with older patients (>60 years old) (OR, 2.61 [95% CI, 2.00 to 3.45] vs. 1.58 [95% CI, 1.38 to 1.81]; P=0.008). Controlling for global region, threshold for hearing impairment, diabetes type, age, gender, or chronic exposure to noisy environments didn't affect the strength of the association.

While hearing loss is a result of aging, researchers noted that the odds ratio remained significant when the sample was stratified by age. Limitations included that there was no ability to control residual confounders linking diabetes and hearing impairment; no data were provided on the prevalence of diabetic complications; and data were limited to adult-onset hearing impairment (although those with earlier onset might have been included).

The authors wrote, “Additional studies are needed to clarify the relationship between diabetes severity and prevalence of hearing impairment and the effect of glycemic control on hearing loss.”