Dose-Dependent Relationship Between Long-Term Metformin Use and the Risk of Diabetic Retinopathy: A Population-Based Cohort Study
Abstract
Recent research has raised concerns about the association between metformin treatment in patients with diabetes mellitus (DM) and an increased risk of diabetic retinopathy. We sought to investigate this relationship, specifically examining if metformin use affects diabetic retinopathy risk in a dose-dependent manner. This study was a secondary data analysis based on a nationwide population database in Taiwan. Patients with new-onset DM, an age of 20 years or older, and a diagnosis of type 2 DM received at any time during 2002–2013 were included in the study. Patients diagnosed with new-onset type 2 DM between 2002 and 2013 were enrolled as the study population. We divided them into two groups: those treated with metformin and those treated with sulfonylureas. A Cox proportional hazards model was employed to estimate the risk of diabetic retinopathy after 5 years of follow-up, including cumulative defined daily dose and intensity of metformin treatment. A total of 241,231 patients received treatment with metformin, while 152,617 patients were treated with sulfonylureas. Compared with patients treated with sulfonylureas, patients who received metformin treatment, at a cumulative defined daily dose 25 defined daily dose), had a 2.43 times higher risk of diabetic retinopathy (95% confidence interval 1.37–4.30) compared with patients treated with sulfonylureas. Patients with DM treated with a lower cumulative dosage of metformin showed beneficial effects that were associated with…
How strong is the evidence?
Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 241,231 participants or records.
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