Metformin Use Reduces the Risk of Peripheral Vestibular Disorder in Diabetic Patients: A Nationwide Population‑based Cohort Study

OBJECTIVE: Peripheral vestibular disorder (PVD) has been linked to diabetes mellitus (DM). Metformin, beyond its glucose-lowering effects, has shown potential neuroprotective and anti-inflammatory properties. However, its relationship with PVD risk in diabetic patients remains unclear. The objective of this study is to evaluate whether metformin use is associated with a reduced risk of developing PVD in patients with DM. STUDY DESIGN: A retrospective matched-cohort design study. SETTING: Data from Taiwan's National Health Insurance Research Database (2000-2021). PATIENTS AND INTERVENTION: Adults aged 18 years and older with a diagnosis of DM were included and classified into metformin users and nonusers. A 1:3 propensity score-matched cohort was constructed based on age, sex, and inclusion date, yielding 44,820 metformin users and 134,460 nonusers. Cox proportional hazards regression models were applied to estimate the incidence of PVD and to evaluate the association between metformin use and PVD risk. Adjusted hazard ratios (aHR) with 95% CI were calculated after controlling for potential confounding variables. MAIN OUTCOME MEASURES: Incidence of PVD in metformin users versus nonusers, and the adjusted hazard ratio of developing PVD associated with metformin use. RESULTS: Over 22 years, PVD incidence was lower in metformin users than in nonusers (4.00% vs. 7.98%, P