Early detection of hearing impairment in type 2 diabetic patients

Background: Hearing impairment is an under-recognized complication of type 2 diabetic patients. Exploring an appropriate technique and method to detect early hearing impairment in diabetic patients is the key to good hearing care. Objectives: The objectives of this study are to evaluate the application effects of extended high-frequency audiometry and distortion product otoacoustic emissions in early detection of hearing impairment in diabetic patients. Materials and methods: The study recruited 65 type 2 diabetic patients with normal hearing thresholds detected by conventional PTA, and 60 control subjects. All subjects completed detailed medical history questionnaires and underwent ENT (Ear, Nose and Throat) physical examinations and laboratory tests. Then they underwent the conventional pure tone audiometry (PTA) tests, extended high frequency audiometry (HFA) and distortion product of otoacoustic emissions (DPOAEs). Audiologic data and the related risk factors of audiology were analyzed. Results: Of 65 diabetic patients, 41 patients (63.1%) suffered from high frequency hearing loss detected by HFA and 58 patients (89.2%) suffered from cochlear dysfunction detected by DPOAEs. The incidence of high frequency hearing loss was 38%, 83.3% and 42.3% at the age of 30-39, 40-49 and 50-59 years, respectively. The factors of age (p = .00) and disease duration (p = .00) were related with the high frequency hearing threshold, while the factor of glycosylated hemoglobin (HbA1c) (p = .716) had no relationship with it. Conclusions and significance: There can be cochlear dysfunction and high frequency hearing loss in diabetic patients with normal hearing thresholds of conventional frequencies. The examinations of HFA and DPOAEs are of great importance for early diagnosis of hearing loss in type 2 diabetic patients.