Metformin and risk of age-related macular degeneration in individuals with type 2 diabetes: a retrospective cohort study

Krishna Gokhale, Nicola Adderley, Anuradhaa Subramanian, Wen Hwa Lee, Diana Han, Jesse Coker , Tasanee Braithwaite, Alastair Denniston, Pearse A Keane, Krishnarajah Nirantharakumar

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Background: Age-related macular degeneration (AMD) in its late stages is a leading cause of sight loss in developed countries. Some previous studies have suggested that metformin may be associated with a reduced risk of developing AMD, but the evidence is inconclusive.

Aims: To explore the relationship between metformin use and development of AMD among patients with type 2 diabetes in the UK.

Methods: A large, population-based retrospective open cohort study with a time-dependent exposure design was carried out using IQVIA Medical Research Data, 1995-2019. Patients aged ≥40 with diagnosed type 2 diabetes were included.

The exposed group were those prescribed metformin (with or without any other antidiabetic medications); the comparator (unexposed) group were those prescribed other antidiabetic medications only. The exposure status was treated as time-varying, collected at 3-monthly time intervals.

Extended Cox proportional hazards regression was used to calculate the adjusted hazard ratios for development of the outcome, newly diagnosed AMD.

Results: A total of 173,689 patients, 57% male, mean (SD) age 62.8 (11.6) years, with incident type 2 diabetes and a record of one or more antidiabetic medications were included in the study. Median follow-up was 4.8 (IQR 2.3-8.3, range 0.5-23.8) years. 3,111 (1.8%) patients developed AMD. The adjusted hazard ratio for diagnosis of AMD was 1.02 (95% CI 0.92 - 1.12) in patients prescribed metformin (with or without other antidiabetic medications) compared to those prescribed any other antidiabetic medication only.

Conclusion: We found no evidence that metformin was associated with risk of age-related macular degeneration in primary care patients requiring treatment for type 2 diabetes.

Original languageEnglish
JournalBritish Journal of Ophthalmology
Early online date3 Feb 2022
Publication statusE-pub ahead of print - 3 Feb 2022


  • Age-related macular degeneration
  • type 2 diabetes
  • metformin
  • primary care
  • electronic health records


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