Auditory acuity in type 2 diabetes mellitus

BACKGROUND AND OBJECTIVES The relationship between diabetes and hearing loss has been debated for many years. Hyperglycemia appears to have an effect on hearing loss and the proposed mechanisms are microangiopathy, neuropathy or a combination of both. The objective of this study was to evaluate a cross section of hyperglycemic subjects with age- and sex-matched normoglycemic controls with pure tone audiometry and compare the differences. MATERIALS AND METHODS Forty-one type 2 diabetes mellitus subjects and 41 age- and sex-matched normoglycemic controls were subjected to a pure tone audiometric assessment followed by evaluation of their glycemic status and degree of glycemic control. The resulting data was statistically analyzed. RESULTS The auditory thresholds in hyperglycemic subjects were higher in all age groups in all the frequencies suggestive of sensorineural hearing loss. The hyperglycemic subjects with poor control of their blood sugar levels (HbA1C > 8%) had elevated auditory thresholds in all the test frequencies. The fasting blood sugar level in hyperglycemic subjects showed a trend towards significant difference at higher frequencies, the postprandial blood sugar levels showed significant differences at higher frequencies. There was no effect of duration of diabetes mellitus on the hearing thresholds in hyperglycemic subjects. CONCLUSION Subjects with hyperglycemia have a sensorineural hearing loss when evaluated with a pure tone audiometer in all frequencies than a normoglycemic control group. The study showed that post prandial blood sugar levels and HbA1C levels had a direct bearing on the auditory acuity of the hyperglycemic subjects.