Patients taking metformin over a two-year period were approximately 5% less likely to develop AMD.

Patients taking metformin over a two-year period were approximately 5% less likely to develop AMD. Photo: Carolyn Majcher, OD. Click image to enlarge.

New research suggests that metformin, a drug often prescribed to treat patients with insulin-resistant diabetes, may potentially have another clinical indication: reducing the risk of age-related macular degeneration (AMD). The study’s findings were recently presented at the American Society of Retina Specialists 2022 annual meeting in New York City.

The study analyzed data from more than 600,000 people, 312,404 who were newly diagnosed with AMD at the time and 312,376 who had no disease and acted as controls. Multivariate and adjusted regression models were used to evaluate patient data over a two-year period and determine the relationship between AMD development and the use of certain medications including metformin, insulin, sulfonylureas and glitazones.

Analysis revealed that patients taking metformin over a two-year period were approximately 5% less likely to develop AMD (odds ratio: 0.94). Interestingly, those who were prescribed a lower dose of metformin had the lowest risk, which may be attributed to the fact that patients taking larger doses of the drug are more likely to have poorly controlled diabetes, although this reasoning is mere speculation.

Metformin wasn’t the only drug to show an association with AMD development; patients on insulin therapy also had a reduced risk of the disease (odds ratio: 0.92). However, a recent article on the study published online by Medscape notes that this medication likely won’t be prescribed to treat AMD in the future due to concerns such as hypoglycemia and the requirement of injections.

Sulfonylureas, another group of medications to treat type 2 diabetes, also seemed to reduce AMD risk (odds ratio: 0.94).

On the other hand, several diabetes drugs analyzed in the study appeared to increase the risk of AMD. These medications included exenatide, sitagliptin and pramlintide (odds ratio: 1.08).

Dimitra Skondra, MD, PhD, associate professor of ophthalmology at the University of Chicago and one of the researchers of the study, said in her interview on the Medscape article, "How great will it be if we can give metformin to our patients when they start developing AMD and lower the disease burden over the years.” She also mentioned that metformin is being studied as a potential therapeutic for other conditions including dementia, cancer and stroke. “I'm also giving metformin to mice using different models of macular degeneration, and I'm seeing an effect there," Dr. Skondra added.

Clinical trials are still needed to confirm the association of metformin and sulfonylureas with reduced AMD risk, but the promising data from this large study certainly piques interest and warrants continued investigation.

Harrison L. Metformin shows potential to prevent macular degeneration. Medscape. Published July 18, 2022. Accessed July 22, 2022.