A Study of Auditory Brainstem Evoked Responses in Type 1 and Type 2 Diabetes Mellitus Patients with Normal Hearing

Auditory Brainstem Evoked Responses in Type 1 and Type 2 Diabetes Mellitus.

Abstract

Background: Diabetes mellitus (DM) is a common metabolic disorders with millions of cases word-wide. Its effect on the functioning of central nervous system (CNS) and peripheral nerves is a matter of current neurological research. Our study aimed to find out changes in auditory brainstem responses if any, in patients with Type 1 & Type 2 DM patients with apparently normal hearing. Subjects and Methods: 50 cases each of Type 1 and Type 2 diabetic patients with apparently normal hearing were chosen along with 50 healthy controls. Patients were classified according to duration of disease. Pure tone audiometry and brainstem evoked response audiometry was performed in all cases. The BERA results were interpreted for latencies of waves I-V and inter-peak latencies I-III, I-V and III-V. Results: Significant delay in absolute latency of wave I, III, IV, V and inter-peak latencies I-V and III-V was seen in Type 1 diabetic patients. In Type 2 diabetic patients, latencies of waves I, II, III, IV and V and inter-peak latencies I-III, I-V and III-V were significantly delayed. Prolonged latencies were not related to type and duration of diabetes. Latencies of waves III and IV were significantly prolonged in type 2 DM patients with fasting blood sugar level >130 mg/dl. Conclusion: BERA is non-invasive and easy to perform test that can detect minor CNS changes at early stage of diabetes and can be used to detect peripheral (auditory nerve) and central neuropathy in diabetics even in absence of clinical signs and symptoms of deafness.