Effect of Diabetes Mellitus on the Hearing Ability of Diabetic Patients

Diabetes mellitus is the most common endocrine disease. Most of the patients suffering from diabetes mellitus complain of hearing loss. Since the previous studies made in this regard were not complete, this study was further conducted in order to evaluate the adverse effects of diabetes mellitus on the hearing ability of the diabetic individuals referring to the clinics of the Medical Universities of Tehran, during 1994-2001 (1373-1380). This investigation was a prospective analytical study carried out on two groups of population in Tehran. The first group consisted of 1500 diabetic patients (case group), and the second group consisting of 1400 normal individuals (control group). The age of the studied population was between 15-55 years. The “case group” consisted of “Diabetic Mellitus Confirmed” patients who were randomly chosen and were willing to cooperate with this study. Initially all of the patients were interviewed and later underwent complete physical examination, audiometry (pure tone, speech, impedance), and “Auditory Brainstem Evoked Response” (ABR) evaluations. The “control group” consisted of individuals that had visited the clinics due to different reasons and according to the standards of the “International Diabetes Federation” they were considered as “Not having Diabetes”. They were also willing to participate in this study. Similar audiometric examinations were performed on this group. Finally the examination results of the two groups were compared. The following results were obtained in this study: 1- The existence of a specific and distinct hearing loss in high frequencies (4-8KHz) between the case and control groups (p<0.05).2- Presence of a significant difference in the hearing level of the NIDDM patients in the high frequencies as compared to the control group (p<0.01).3- There was a distinct hearing loss in the “Complicated Diabetic Patients” in the high frequencies as compared to the normal control group (p=0.01).4- Patients with short term diabetes mellitus had normal level of hearing, but in patients suffering from long term diabetes mellitus, there was a significant hearing impairment in the high frequencies (4-8 KHz) as compared to the control group (p<0.005). ConclusionDue to the prevalence of diabetes mellitus in the community and the presence of sensorineural hearing loss (especially bilateral) in the high frequencies in a significant number of studied patients, it’s recommended to carry out a complete diagnostic audiometric evaluation in all the diabetic patients and to repeat the auditory tests regularly every year. With this method, we can not only be informed of the “Hearing status” of the patient but also use the results as a guideline and outlook for a better control of diabetes and its related complications. (Tanaffos 2003; 2(6): 51-58)