Researchers recently studied the use of metformin for AMD and deemed it a potential preventive therapy for the disease. The antidiabetic drug had previously demonstrated protective properties in other age-related diseases.

The case-control study included 312,404 patients aged 55 and older with newly diagnosed AMD and 312,376 age-matched controls. The researchers analyzed metformin dosage and prescribed medication exposure.

The researchers noted that the case group had a slightly higher percentage of diabetic patients compared with control (26% vs. 25.5%, respectively). They found that metformin use was associated with a reduced odds of developing AMD and that this association was dose-dependent. Low to moderate doses of metformin had the greatest benefit. Dosages exceeding 1,080g didn’t demonstrate a lower risk of AMD development over two years.

“Both the reduction in odds ratio and the dose-dependent response were preserved in a cohort consisting only of patients with diabetes,” the researchers noted in their paper. In diabetic patients without coexisting diabetic retinopathy (DR), metformin use was associated with a decreased odds ratio of AMD. However, the use of this drug was a risk factor in patients with DR.

The researchers concluded that metformin may reduce the odds of AMD development, with low to moderate doses having the largest effect. They cautioned, however, that metformin doesn’t appear to be protective in patients with diabetes and coexisting DR. They urged prospective clinical trials for the use of metformin for AMD prevention.

Blitzer AL, Ham SA, Colby KA, et al. Association of metformin use with age-related macular degeneration: a case-control study. JAMA Ophthalmol. January 21, 2021. [Epub ahead of print].