Metformin use linked to reduced odds of AMD in non-diabetic population

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A case-control study, involving a large population without diabetes, suggests that the use of metformin is associated with a reduced risk of developing age-related macular degeneration (AMD).

The study found that individuals exposed to metformin in the 2 years before AMD diagnosis had lower odds of developing AMD. Importantly, this potential protective effect was observed across different dosing quartiles of metformin and was not found to be dose-dependent.

The study matched patients aged 55 years or older with AMD and controls without AMD in a 1:1 ratio, factoring in year, age, anemia, hypertension, region, and Charlson Comorbidity Index score. Subgroup analyses were conducted to explore the association between metformin use and AMD staging, specifically in cases with dry AMD and their matched controls.

Among the 231,142 patients identified with any AMD and the 232,879 matched controls without AMD, none of whom had a diabetes diagnosis, approximately 1.0% of cases and 1.3% of controls were exposed to metformin in the 2 years preceding their index visit.

After adjustment for known risk factors for AMD, including sex, hyperlipidemia, smoking, and exposure to other antidiabetic medications, the study found that any metformin use was associated with reduced odds of both any AMD development and dry AMD development. Interestingly, this association did not appear to be dose-dependent, as adjusted odds ratios for AMD development did not differ across dosing quartiles.

The implications of these findings are substantial, suggesting that metformin may have a protective effect against the development of AMD in a non-diabetic population. The study’s authors emphasize the importance of further research through prospective clinical trials to validate these findings and explore metformin’s potential role in preventing AMD.

Aggarwal S, Moir J, Hyman MJ, et al. Metformin Use and Age-Related Macular Degeneration in Patients Without Diabetes. JAMA Ophthalmol. Published online November 30, 2023. doi:10.1001/jamaophthalmol.2023.5478