ASRS Live: Diabetic therapy metformin may have protective effect against AMD

ASRS 2022 is being held at the Javits Center in New York. (File photo)

Reviewed by Dimitra Skondra, MD, PhD

Metformin, a frequently prescribed drug to treat diabetes, may have the potential to be a novel therapy for age-related macular degeneration (AMD), according to Dimitra Skondra MD, PhD, who presented a poster on the topic at the American Society of Retina Specialists 2022 annual meeting in New York.

Skondra is an associate professor of Ophthalmology and Visual Science, director of the J. Terry Ernest Ocular Imaging Center, founder/leader, Retina Microbiome Team, Vitreoretinal Service, at the University of Chicago.

This protective effect is known to be present against other age-associated diseases, but the importance of such a finding in diabetes cannot be over-emphasized.

Dimitra Skondra, MD, PhD

Skondra and her colleagues conducted a retrospective case-control study to take a close look at the the relationship between metformin and other antidiabetic medications in patients with AMD. The authors used a large health insurance claims database to identify patients who had been newly diagnosed with AMD between January 2008 and December 2017.

A total of 312,404 patients and 312,376 matched controls were included in the study.

Important finding

“We found that metformin use was associated with reduced odds of developing AMD (odds ratio [OR], 0.94 [95% CI, 0.92-0.96]), Skondra reported.

The low-to-moderate doses of metformin carried the greatest potential benefit. The former covers doses of 1-270 grams/2 years; OR, 0.91 [95% confidence interval [CI], 0.88-0.94]; and the latter 271-600 grams/2 years; OR, 0.90 [95% CI, 0.87-0.93]).

In contrast, doses that exceeded 1080 grams/2 years were not associated with reduced odds of developing AMD.

Both the reduced ORs and the dose-dependent response were preserved in the diabetic patients-only cohort, that is, metformin was associated with a decreased OR of development of AMD in patients with diabetes who did not have diabetic retinopathy (OR, 0.93 [95% CI, 0.91-0.95]); however, this was not the case when patients also had diabetic retinopathy (OR, 1.07 [95% CI, 1.01-1.15]).

Another finding in the patients in the diabetic cohort was an independent protective effect against AMD development associated with the use of insulin (OR, 0.92 [95% CI, 0.90-0.95], p < 0.001), and sulfonylureas (OR, 0.94 [95% CI, 0.92-0.96], p < 0.001). When analyzed in combination with metformin versus neither of those medications, insulin (OR, 0.89 [95% CI, 0.83-0.97], p = 0.004) and sulfonylureas (OR, 0.91 [95% CI, 0.84-0.98], p = 0.01), the analysis showed a protective effect as well.

Subjects taking insulin or sulfonylureas alone had a similar risk of developing AMD as those taking metformin alone (OR, 0.96 [95% CI, 0.89-1.01] and OR, 0.98 [95% CI, 0.90-1.05), respectively). Patients receiving exenatide, sitagliptin (Januvia, Merck), or pramlintide (Symlin, Bristol-Myers Squibb), other diabetic medications, had a higher risk of developing AMD (OR, 1.08 [95% CI, 1.05-1.11], p < 0.001), although when taken with metformin the increased risk was no longer seen (OR, 1.04 [95% CI, 0.97-1.13]).

Another finding was that subjects taking sulfonylureas with metformin had an even greater decreased risk of AMD development compared to those taking metformin alone (OR, 0.94 [95% CI 0.91-0.97], p < 0.001).

“The data suggest that metformin may be a novel AMD therapeutic strategy and provide the basis for future studies,” Skondra concluded.

Dimitra Skondra, MD, PhD

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Skondra has no financial disclosures related to this content.