Image of a clinician advising a patient about diabetes care.

The diabetes drug metformin may protect against the development of age-related macular degeneration, a common cause of blindness that to date has no effective preventive measures, according to researchers.

The findings come from a large, case-control study of data from U.S. insurance claims. Participants aged 55 years and older with newly diagnosed AMD were matched with a control group.

Metformin, commonly used to help manage blood sugar in diabetes, has been shown to protect against age-related disease, and reduce the odds of cardiovascular events. When investigators examined metformin dosage and exposure to other prescribed medications in the study population, the drug’s use was associated with decreased odds of developing AMD, reported lead author Dimitra Skondra, M.D., Ph.D, of the University of Chicago Medical Center.

The greatest benefit appeared to occur at low to moderate dosages.

When they looked only at patients with diabetes, there was a dose-dependent decrease in the odds of patients developing AMD, Skondra and colleagues wrote. Notably, however, metformin did not appear to be protective in patients who had diabetes and a diagnosis of diabetic retinopathy (damage to blood vessels in the eye caused by high blood sugar).

The current findings suggest that clinicians could use metformin as part of a new therapeutic strategy to help prevent AMD, Skondra and team concluded.

AMD is associated with aging, and damages sharp and central vision, according to the Centers for Disease Control and Prevention. 

Full findings were published in JAMA Ophthalmology.

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