Diabetes mellitus and hearing loss: clinical and histopathologic relationships.

We compared audiometric and clinical histories with findings in temporal bones of eight diabetics and ten normal controls matched for age and sex. The group with diabetes mellitus had significantly more hearing loss than the normal control group (p less than .01). Only patients with diabetes had microangiopathy. Patients with microangiopathic involvement of the endolymphatic sac had significantly greater hearing loss than patients without such involvement (p less than .01). Microangiopathy in the stria vascularis was highly significant in the diabetics (p less than .001); however, they did not have a significant hearing loss. Diabetic patients with basilar membrane microangiopathy had significantly lower percentages of histologically normal hair cells (p less than .05) and stria vascularis cells (p less than .05) and significantly greater hearing loss (p less than .01) than diabetic patients without such pathologic changes. Results of this study suggest that diabetic sensorineural hearing loss results from microangiopathic involvement of the endolymphatic sac and/or basilar membrane vessels.