Effect of Adding Metformin to Standard High Dose Systemic Steroid Therapy in Non-Diabetic Patients With Sudden Sensorineural Hearing Loss

Background and Objectives Sudden sensorineural hearing loss (SSNHL) is commonly treated with high-dose systemic corticosteroids, yet recovery remains incomplete in a substantial proportion of patients. Metformin has pleiotropic anti-inflammatory, immunomodulatory, and vascular-protective effects and may mitigate steroid-induced dysglycemia. This study evaluated whether adding metformin to the standard high-dose glucocorticoid therapy improves hearing outcomes in nondiabetic SSNHL.Subjects and Method This retrospective observational cohort study included patients treated for idiopathic SSNHL at a single tertiary center (July 2020-July 2025). All patients received oral methylprednisolone of 48 mg/day for 10 days followed by taper; non-responders received intratympanic dexamethasone (up to four injections). The metformin group additionally received metformin of 500 mg/day for 4 weeks. Variable ratio propensity score matching (caliper 0.2) was controlled for age, vertigo, onset-to-treatment interval, and baseline pure-tone average (PTA). Outcomes were changes in the PTA and word recognition score (WRS), and American Academy of Otolaryngology-Head and Neck Surgery Foundation recovery categories. Groupby-time interaction was tested using a linear mixed model.Results After matching, 68 patients were analyzed (control n=44; metformin n=24). Both groups showed significant improvement in PTA and WRS; however, between-group differences were not significant (PTA interaction p=0.779; WRS interaction p=0.965). Complete recovery occurred in 43.2% of controls and 33.3% of metformin patients.Conclusion In nondiabetic SSNHL, short-term low-dose metformin added to the standard high-dose steroid therapy did not provide additional hearing benefit.