A widely used medication for type 2 diabetes, metformin, may reduce the risk of developing intermediate age-related macular degeneration (AMD), according to a new University of Liverpool study. Researchers analyzed retinal photos from about 2,000 people with diabetes aged 50 and older who underwent routine diabetic eye screening in Liverpool over five years. They found that people taking metformin had 37% lower odds of developing intermediate AMD during that period compared with those not on the drug.
Lead researcher Nicholas Beare, MD, called the finding promising because most people with AMD currently have limited treatment options. He and colleagues say the next step is testing metformin for AMD in clinical trials to determine whether it can help preserve sight.
Independent experts urge caution. Theodore Leng, MD (Stanford), noted limitations in the Liverpool analysis and pointed to a 2025 JAMA study of 1.6 million people that found no significant link between metformin and advanced AMD. Benjamin Bert, MD, an ophthalmologist in California, emphasized that the Liverpool study included only older adults with diabetes, so it’s unclear whether metformin would benefit a broader population without diabetes.
About 20 million people over age 40 in the U.S. are affected by AMD. The disease damages the macula—the central part of the retina—causing progressive central vision loss and, in advanced cases, blindness. Dry AMD (85–90% of cases) involves drusen deposits beneath the macula; wet AMD (10–15%) involves abnormal blood vessels and can cause rapid, severe vision loss. Early symptoms include difficulty seeing in low light, reduced clarity at distance and near, and less sharp colors; later symptoms include central blurriness, dark spots, and trouble recognizing faces.
Current management options include the AREDS2 vitamin formulation, which can lower progression risk from intermediate to advanced AMD by about 25%, and newer approaches such as FDA-authorized photobiomodulation for dry AMD. There is no universal cure.
Metformin is an oral generic medication that lowers blood glucose by reducing liver glucose production, decreasing absorption from food, and improving insulin sensitivity. Common side effects include diarrhea, nausea, headache, and indigestion. It carries a boxed warning for the rare but serious risk of lactic acidosis. Metformin is not approved for weight loss, though some people lose weight while taking it.
Clinicians caution against prescribing metformin solely to prevent or treat AMD in people without diabetes. Potential harms include hypoglycemia in those prone to low blood sugar and other adverse effects. For patients already prescribed metformin for diabetes, continuing the medication is reasonable given its overall safety, but expectations about AMD protection should be measured.
Experts recommend evidence-based steps to reduce AMD risk and progression: regular eye exams (possibly every six months for at-risk patients), taking AREDS2 supplements when indicated, wearing sunglasses or a brimmed hat outdoors, avoiding tobacco smoke, following a healthy diet (such as the Mediterranean diet), and exercising regularly. Further randomized clinical trials are needed to confirm whether metformin can be an effective treatment for AMD.
