A new study shows that patients with diabetes have a significantly higher prevalence of hearing impairment than those who do not have diabetes.

The study, to be published in the Journal of Clinical Endocrinology & Metabolism (JCEM), comes in the wake of several other studies that investigated the relationship between diabetes and hearing impairment, but provided inconsistent findings. The research was prompted by the statistic that the number of people with impaired hearing more than doubled from 1995 to 2004.

“The association of hearing impairment with diabetes is controversial, but it is believed that over time, high blood glucose levels can damage vessels in the stria vascularis and nerves diminishing the ability to hear,” said Chika Horikawa, lead author of the study and a dietitian at Niigata University. “In our study we found that persons with diabetes had more than two times higher prevalence of hearing impairment than those without diabetes.”

The meta-analysis study looked at 13 past cross-sectional studies that included a total of 20,194 patients. Researchers assessed hearing impairment by pure-tone audiometry. The results showed that the strength of the association between diabetes and hearing impairment was not influenced by age, gender, or noisy environments.

“Our results propose that diabetic patients be screened for hearing impairment from earlier age compared with non-diabetics, from the viewpoint of prevention of several health problems such as depression and dementia caused by hearing impairment,” said Horikawa.