Risk of Non-infectious Uveitis with Metformin Therapy in a Large Healthcare Claims Database

PURPOSE: To determine if metformin is associated with non-infectious uveitis (NIU). METHODS: Patients in an insurance claims database who initiated metformin (n=359,139) or other oral anti-diabetic medications (n=162,847) were followed for NIU development. Both cohort and case-control analyses were performed to assess differing exposure lengths using Cox and conditional logistic regression, respectively. RESULTS: The hazard ratio (HR) for incident NIU was not significantly different between the metformin and non-metformin cohorts [HR=1.19, 95% Confidence Interval (CI): 0.92-1.54, P=0.19]. The case-control analysis similarly showed no association between any metformin use 2 years before the outcome date and NIU [Odds ratio (OR)=0.64, 95% CI: 0.39-1.04, P=0.07]. However, there was a protective association between cumulative metformin duration [445-729 days adjusted OR (aOR)=0.49, 95% CI: 0.27-0.90, P=0.02) and dosage (>390,000 mg aOR=0.44, 95% CI: 0.25-0.78, P=0.001] compared with no metformin use. CONCLUSIONS: Our results suggest metformin use for longer durations may be protective of NIU onset.