Diabetes Drug Metformin May Help Prevent Risk of Geographic Atrophy

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The popular anti-diabetic drug metformin may also be a beneficial alternative treatment to prevent geographic atrophy (GA) development in patients with age-related macular degeneration (AMD).

A recent study demonstrated an link between metformin use and a decrease in new diagnoses of GA after controlling for other AMD risk factors, with a persistent association in patients without diabetes.

Given the study's findings, the current limitation of available GA therapies, and the greater availability of the proven drug metformin, investigators believe the treatment could be a promising option to help prevent GA in patients with worsening AMD.

The late-stage forms of AMD are separated into the neovascular (or "wet") form, defined by choroidal neovascularization (CNV), and GA, characterized by progressive and irreversible photoreceptor and retinal pigment epithelium (RPE) loss. Approximately 40 percent of patients who progress to GA later develop blindness—recent approvals from the US Food and Drug Administration (FDA) have marked the first two treatments for GA: pegcetacoplan (Empaveli) and avacincaptad pegol (Izervay).

However, these treatments only slow the progression of the disease and do not prevent its onset or improve visual acuity. Recent evidence has linked metformin with a reduced likelihood of AMD development, but the conclusions were limited. No observational study between metformin and AMD development has considered GA preventionas its primary outcome.

Investigators conducted a case-control study to observe the association between metformin and GA, identifying patients aged at least 60 years old with new-onset GA diagnoses between 2017 and 2021.

Each GA case was matched with propensity scores estimated by age, region, Charlson Comorbidity Index (CCI) and hypertension to a control of the same year. Controls matched the same inclusion criteria but did not have a GA diagnosis. Exposures, defined as antidiabetic medications, required an outpatient prescription drug claim in the year before and including the index visit date.

The full sample identified 10,505 cases with new-onset coding of GA, with a mean age of 82.1 years old and consisting of 63 percent female patients. Investigators matched these cases with 10,502 controls without GA, with a mean age of 82.1 years and consisting of 57 percent female patients.

Among the population, 2894 (27.6 percent) cases and 2935 (28 percent) controls were diagnosed with diabetes, with 1149 (10.9 percent) GA cases and 1277 (12.2 percent) controls exposed to metformin. Multivariable regression, adjusted for AMD and other anti-diabetic medications, revealed metformin reduced the likelihood of new-onset coding of GA by 12 percent.

For the sample of patients without diabetes, investigators identified 7611 cases with GA and 7608 matched controls without GA. Only 0.4 percent of GA cases and 0.8 percent of controls were exposed to metformin. In multivariable regression analysis, metformin decreased the odds of developing new-onset coding of GA by 47 percent.

“As more recent administrative data become available, additional studies are needed to confirm the associations identified herein and to motivate a clinical trial,” investigators wrote.

An original version of this article was published on sister site HCPLive.