Safety of Metformin in Psoriasis Patients with Diabetes Mellitus: A 17-Year Population-Based Real-World Cohort Study

Context The safety of metformin usage by diabetic psoriasis patients is unclear. Objective To investigate the real-world safety of metformin in psoriatic patients with type 2 diabetes mellitus (T2DM). Design We used the National Health Insurance Research Database to perform a cohort study. Based on metformin and other antidiabetic agent prescriptions, we divided all psoriasis patients with T2DM into the metformin group and the nonmetformin group. The outcomes included all-cause mortality, severe psoriasis, hospitalization due to psoriasis, and any cause for readmission. Results The metformin group (n = 5520) and the nonmetformin group (n = 3062) did not significantly differ in the risk of all-cause mortality [hazard ratio (HR) 1.08; 95% CI, 0.90 to 1.30], severe psoriasis (HR, 0.95; 95% CI, 0.80 to 1.09), psoriasis-related admission (HR, 1.32; 95% CI, 0.90 to 1.93), and any-cause readmission (HR, 0.99; 95% CI, 0.90 to 1.11). The dose-response analysis found no significant increase in the risk of severe psoriasis and psoriasis-related admission, even with more than 80 defined daily doses or 1000 mg daily dose of metformin prescribed (P for linear trend > 0.05). Conclusion Metformin can be prescribed for diabetic psoriasis patients without safety concerns.