Hearing loss among patients with type 2 diabetes mellitus: a cross-sectional study

BACKGROUND: Hearing loss is an underestimated comorbid condition in type 2 diabetes. OBJECTIVES: Investigate hearing loss as a comorbidity associated with type 2 diabetes mellitus and evaluate the factors associated with hearing loss. DESIGN: Cross-sectional. SETTING: Tertiary care center, diabetes clinic. PATIENTS AND METHODS: Patients with type 2 diabetes, aged 30 to 60 years, were randomly selected to participate. All patients underwent clinical ear examinations and were referred for full audiological evaluation. Otoacoustic emission was used to assess inner function, tympanometry to assess middle-ear function, and pure tone air/bone audiometry to assess hearing sensitivity. Risk factors for hearing loss were assessed by multivariate logistic regression. MAIN OUTCOME MEASURES: Frequency, severity and risk factors for hearing loss. SAMPLE SIZE: 157 RESULTS: Of the 157 patients, 77 had hearing loss in both ears (49.0%), 13 in the right ear only (8.3%), 14 in the left ear only (8.9%), and 53 (33.8%) had normal hearing. In the 181 ears with sensorineural hearing loss, 90 had mild loss (49.7%), 69 moderate loss (38.2%), 16 severe loss (8.8%) and 6 had profound loss (3.3%). Disabling hearing loss was observed in 46 (29%) patients. A higher frequency of hearing loss was present in patients with glycated hemoglobin levels =8%. In the multivariate logistic regression analysis, the most important factors associated with hearing loss were longer diabetes duration, poor glycemic control and the presence of hypertension. CONCLUSIONS: Hearing loss is an underestimated comorbid condition in type 2 diabetes that warrants frequent hearing assessments and management. Strict glycemic and hypertension control is essential for the minimization of the effects of diabetes on hearing sensitivity. LIMITATIONS: Small sample size, limited age window (30-60 years), which was chosen to eliminate the natural aging effect on hearing. Cross-sectional nature was not ideal for the assessment of causality.