Common diabetes drug metformin may slow age-related vision loss.

An observational study of about 2,000 people with diabetes found that those over 55 taking metformin were 37% less likely to develop intermediate age-related macular degeneration over five years; researchers say the result shows an association but does not prove causation and call for clinical trials.

A new observational study reports a link between metformin use and lower rates of intermediate age-related macular degeneration (AMD) among older adults with diabetes. Researchers at the University of Liverpool examined retinal images collected in routine diabetic eye screenings over five years. The result is notable because treatment options for many forms of AMD are limited and researchers want to explore potential new approaches. Key findings: - Among people with diabetes aged over 55, those taking metformin were reported to be 37% less likely to develop intermediate AMD over five years compared with those not taking the drug. - The team reviewed retinal photos from about 2,000 people who had routine diabetic eye disease screenings during the five-year period. - Analyses adjusted for factors such as age, sex, and duration of diabetes, and the study design was observational, which limits conclusions about cause and effect. - The researchers did not have data on the doses of metformin taken or on patients' adherence to prescriptions, and the study included only people with diabetes, so effects in people without diabetes are unclear. - The Mayo Clinic notes metformin is an off-patent, widely used medication that can cause digestive side effects and vitamin B12 deficiency in some patients. Summary: The study suggests an association between metformin use and a lower incidence of intermediate AMD in older adults with diabetes, but it does not establish that metformin caused the reduced risk. Lead researchers said clinical trials are needed to test metformin as a potential treatment for AMD, and further research will be required to determine whether the association holds in broader populations.