In the US, AMD is the leading cause of irreversible blindness in adults older than 50 years. As the older adult population increases worldwide, there is a growing economic burden of AMD. Currently, there are no efficacious preventive measures for AMD development or available treatments for the nonexudative form, which accounts for 90% of cases.
Metformin, the most commonly prescribed oral antihyperglycemic drug for diabetes, has been shown to have antiaging and protective effects against many age-associated diseases. In epidemiology studies, metformin lowers the risk of developing cardiovascular disease, stroke, cancer, dementia, and primary open-angle glaucoma. Metformin also reduces inflammatory markers and increases life span in murine models. These exciting findings have led to the Targeting Aging With Metformin (TAME) trial, a prospective randomized clinical trial to assess metformin’s antiaging effects.
Given the known antiaging effects of metformin and its relatively safe adverse-effect profile, the authors of this study sought to determine if the use of metformin is associated with reduced odds of developing AMD in a large, nationwide sample. They also investigated a potential dose-dependent association in the study population, as well as in a subgroup of only patients with diabetes. Additionally, the authors evaluated whether the findings were dependent on the presence or absence of coexisting diabetic retinopathy (DR).
The authors of the study, published in JAMA Ophthalmology, are Dr. Andrea L. Blitzer and Dr. Dimitra Skondra of the Department of Ophthalmology and Visual Science, University of Chicago Medical Center; Ms. Sandra A. Ham of Center for Health and the Social Sciences, The University of Chicago; and Dr. Kathryn A. Colby of Department of Ophthalmology, New York University, New York.
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The authors found that not only does metformin reduce the odds of developing AMD, but that this outcome is strongest at low to moderate doses and is only seen in the absence of coexisting DR. This study highlights metformin as a possible therapeutic intervention to prevent or slow the progression of AMD. The authors add that future studies will be important to further validate and confirm this finding, in addition to determining the molecular mechanisms involved and which pathogenic pathways of AMD are affected by metformin. If a protective effect of metformin is confirmed in clinical trials, they believe this may lead to a novel therapeutic strategy for this disease, which is the leading cause of blindness in older adults and has no previously established preventive measures.