Hyperglycemia as a Potential Prognostic Factor of Idiopathic Sudden Sensorineural Hearing Loss

Objective Hyperglycemia is not identified as a significant prognostic factor for idiopathic sudden sensorineural hearing loss in any literature. Therefore, we investigated the prognostic value of hyperglycemia in predicting hearing recovery. Study Design A retrospective cohort study. Setting Tertiary university hospital. Subjects and Methods Patients were classified into 3 groups according to their glucose tolerance using the 75-gram oral glucose tolerance test and hemoglobin A1c test as follows: (1) a normal glucose tolerance group, (2) a prediabetes group, which included patients with impaired glucose tolerance and/or impaired fasting glucose levels, and (3) a diabetes mellitus group. Results Among 94 patients with idiopathic sudden sensorineural hearing loss, 45 were classified into the normal glucose tolerance group, 28 into the prediabetes group, and 21 into the diabetes mellitus group. The recovery rate of the normal glucose tolerance group was not higher than that of the diabetes mellitus group (P = .140). However, when the prediabetes and diabetes mellitus groups were collectively defined as the impaired glucose regulation (hyperglycemia) group, the hearing recovery rate of the normal glucose tolerance (normoglycemia) group was significantly better than that of the impaired glucose regulation group (P = .038). Conclusion We suggest that hyperglycemia may be a potential negative prognostic factor for hearing recovery in idiopathic sudden sensorineural hearing loss. Further interventional studies should be followed to determine whether hearing outcomes of the impaired glucose regulation group may be improved to the same extent as those of the normal glucose tolerance group after strict glycemic control.