A University of Liverpool study suggests metformin, a common drug for type 2 diabetes, may lower the chance of developing intermediate age-related macular degeneration (AMD). Researchers reviewed retinal photographs from roughly 2,000 people with diabetes, all aged 50 or older, who underwent routine diabetic eye screening in Liverpool over a five-year period. After adjustment, people taking metformin had about 37% lower odds of developing intermediate AMD during that timeframe compared with people not taking the drug.
The study’s lead investigator, Nicholas Beare, MD, described the finding as promising because treatment options for most AMD patients remain limited. He and colleagues say the next step is to test metformin in randomized clinical trials to determine whether it can preserve vision or slow disease progression.
Independent experts urge caution in interpreting the results. Theodore Leng, MD (Stanford), noted methodological limitations in the Liverpool analysis and pointed out a large 2025 JAMA study of 1.6 million people that did not find a significant association 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 is unclear whether metformin would have the same effect in people without diabetes.
Background on AMD: About 20 million U.S. residents over age 40 are affected by AMD. The disease damages the macula—the central portion of the retina responsible for detailed vision—leading to progressive central vision loss and, in advanced cases, blindness. Dry AMD accounts for about 85–90% of cases and is characterized by drusen (fatty deposits) under the macula. Wet AMD (10–15%) involves abnormal blood vessels and can cause rapid, severe vision loss. Early symptoms can include difficulty seeing in low light, reduced clarity for near and distance tasks, and less vivid colors; later signs include central blurriness, dark or blank spots, and trouble recognizing faces.
Current management: There is no universal cure. Evidence-based measures include the AREDS2 vitamin formulation, which can reduce the risk of progression from intermediate to advanced AMD by about 25% when used as directed, and newer options such as FDA-authorized photobiomodulation for certain dry AMD patients.
About metformin: Metformin is an oral, generic medication that lowers blood glucose by reducing hepatic glucose production, decreasing intestinal glucose absorption, and improving insulin sensitivity. Common side effects include diarrhea, nausea, headache, and indigestion. Rare but serious lactic acidosis is noted in a boxed warning. Metformin is not FDA-approved for weight loss, though some patients experience weight changes.
Clinical guidance: Physicians generally advise against prescribing metformin solely to prevent or treat AMD in people without diabetes because potential harms may outweigh uncertain benefits. Risks can include hypoglycemia in susceptible individuals and other adverse effects. For patients already taking metformin for diabetes, continuing the medication is reasonable given its established safety and benefits, but any expectation that it will prevent AMD should be cautious.
Recommendations to reduce AMD risk and slow progression remain unchanged: regular dilated eye exams (more frequent monitoring, such as every six months, may be appropriate for higher-risk patients), use of AREDS2 supplements when indicated, sun protection with sunglasses or a brimmed hat, avoidance of tobacco smoke, following a healthy diet (for example, a Mediterranean-style diet), and regular physical activity. Randomized clinical trials will be needed to confirm whether metformin is an effective AMD therapy.
