Another hazard of diabetes: Hearing loss

Hearing impairment is associated with type 2 diabetes in adults, likely due to diabetes-induced microangiopathy, neuropathy, and mitochondrial damage to the auditory system, according to a review article published in the journal Current Diabetes Reports.

Given this finding, clinicians should include hearing testing in their management of patients with type 2 diabetes, the authors concluded.

“The association between diabetes and hearing impairment tends to be stronger in studies that included younger participants, perhaps because in older samples, other causes of age-related hearing impairment may mask the contribution of diabetes to the impairment. This factor in itself lends weight to the notion that type 2 diabetes can damage hearing,” said study co-author Elizabeth Helzner, PhD, Assistant Professor in the Department of Epidemiology and Biostatistics in the School of Public Health at SUNY Downstate Medical Center, Brooklyn, NY.

One of these studies, for instance, was the National Health and Nutrition Examination Survey (NHANES). This large epidemiologic study found that in adults 40 to 69 years old, the prevalence of low- or mid-frequency hearing impairment was 21.3% among those with diabetes compared with 9.4% among those without diabetes.

Scientists don’t yet know exactly how diabetes leads to hearing loss, but a possible mechanism may be that hyperglycemia combines with oxidative stress, which results in cochlear microangiopathy and auditory neuropathy, conjectured Dr. Helzner and her co-author, Kevin J. Contrera, MPH, MD, of Johns Hopkins University School of Medicine, in Baltimore, MD.

They added that well-designed longitudinal studies are necessary in order to find out whether patients with diabetes are at increased risk of early-onset hearing impairment, and whether the progression of hearing impairment varies based on diabetes status and disease management factors.

As more Americans progress to type 2 diabetes, the numbers of people with hearing impairment may also grow. Currently, 16% of American adults have hearing impairment. By age 70, that percentage jumps to two-thirds of adults.

“Diabetes prevention efforts, and the careful management of diabetes once diagnosed, can potentially play a role in reducing the burden of disabling hearing impairment in the population,” the authors concluded.