Hearing Loss and Associated Factors in Iranian Patients with Type 2 Diabetes: A Case-Control Study

Background: Hearing loss is an important impairment that occurs in the diabetics and affects their quality of life. There is still a paucity of studies on the relationship between diabetes and hearing loss. Objectives: This case-control study compared the prevalence of hearing loss in a sample of diabetics with that in an age and sex matched group of healthy controls. Methods: Cases were consecutively selected from the diabetics registered in two diabetes centers during February to December 2013. Controls were age and sex matched healthy volunteers admitted to a blood bank. Pure tone audiometric test (PTA) was performed by audiometer for the evaluation of hearing impairment. Then, the existence of hearing impairment in different intensities was compared between the two groups considering the effect of diabetes duration, BMI, and serum creatinine (Cr) level. Results: Eighty diabetics and eighty healthy controls were included. Hearing loss in sounds with high frequencies was more common in the diabetics than the controls. The mean serum creatinine level was significantly higher in the diabetics with hearing loss than those without hearing loss at noise frequencies of 4 KHz and 8 KHz (P < 0.05). Meanwhile, hemoglobin A1C, duration of diabetes, and body mass index were not associated with hearing loss. Conclusions: According to the results, hearing impairment in high frequency sounds was more common in the diabetics than the healthy individuals. Also, the severity of hearing loss in patients with diabetes was associated with the levels of creatinine (diabetic nephropathy). The hypothesis of the relationship between diabetes and hearing loss through nephropathy should be more examined in future studies