Metformin may act as protective shield against Acute Macular Degeneration in Diabetics

In a groundbreaking study, researchers have uncovered a potential link between the use of the widely prescribed diabetes medication, metformin, and a reduced risk of developing age-related macular degeneration (AMD) in individuals without diabetes. The findings, gleaned from a comprehensive case-control study using data from the Merative MarketScan Research Database spanning from 2006 to 2017, shed light on the medication's impact on eye health. The study results were published in the journal JAMA Ophthalmology. 

Studies in the past have shown that metformin might offer protection against the onset of age-related macular degeneration (AMD), as indicated by observational studies. Nevertheless, its efficacy in individuals without diabetes remains uncertain. Hence researchers conducted a case-control study by utilising data from Merative MarketScan Research Database to assess the association between metformin use and the development of AMD in patients without diabetes.

The study, which included 2,31,142 patients with AMD and 2,    32,879 matched controls without AMD, focused on individuals aged 55 years or older, none of whom had been diagnosed with diabetes. The meticulous matching process involved aligning participants based on various factors, including year, age, anemia, hypertension, region, and Charlson Comorbidity Index score.

Researchers honed in on metformin exposure in the 2 years preceding the index date, which was either the diagnosis of AMD for cases or a randomly selected eye examination for controls. Notably, the cumulative dose of metformin was categorized into quartiles for analysis (1-270, 271-600, 601-1080, and >1080 g/2 y). Concurrent exposure to other antidiabetic medications was also considered.The likelihood of developing new-onset age-related macular degeneration (AMD) was evaluated through multivariable conditional logistic regression, accounting for established AMD risk factors such as female sex, hyperlipidemia, smoking, and exposure to other antidiabetic medications. Additionally, asymptotic Cochran-Armitage tests for trend were conducted.

Findings: 

• 231,142 AMD cases and 232,879 matched controls were identified, all without a diabetes diagnosis.
• Metformin exposure in the 2 years prior to the index date was associated with reduced odds of any AMD development (adjusted odds ratio [AOR], 0.83; 95% CI, 0.74-0.87).
• Subgroup analyses for dry AMD also showed reduced odds with metformin use (AOR, 0.85; 95% CI, 0.79-0.92).
• The association did not appear to be dose-dependent, as odds ratios were consistent across dosing quartiles.
• Asymptotic Cochran-Armitage tests for trend did not reveal significant trends for any or dry AMD.

While metformin is primarily recognized for its role in managing diabetes, this study suggests a broader horizon for its impact on eye health. As the research community looks toward future investigations, these findings prompt a reevaluation of metformin's potential benefits beyond its established therapeutic use. The implications could be transformative, offering new avenues for preventing a condition that significantly impacts the aging population's visual health.

Further reading: Aggarwal S, Moir J, Hyman MJ, et al. Metformin Use and Age-Related Macular Degeneration in Patients Without Diabetes. JAMA Ophthalmol. Published online November 30, 2023. doi:10.1001/jamaophthalmol.2023.5478