Abstract
Purpose :
Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the elderly and no treatments exist to prevent vision loss in dry AMD (dAMD). Metformin is a Food and Drug Administration approved oral therapeutic utilized in diabetes mellitus. Recent pre-clinical data and a small, retrospective study suggest that metformin has a protective effect on developing AMD. Therefore, we sought to determine the association between metformin and dAMD in a large nationwide cohort.
Methods :
A large U.S. insurance claims database was reviewed to identify individuals with a diagnosis of diabetes mellitus and age ≥55 years who were enrolled for ≥2 years without a previous diagnosis of AMD. The primary exposure was active or prior metformin use determined from prescription fill records. A time updating Cox proportional hazard regression was performed to estimate the hazard ratio (HR) of developing dAMD with metformin exposure. Covariates included demographic factors, non-proliferative diabetic retinopathy, severity of diabetic complications, and other systemic comorbidities.
Results :
Of the 1,007,213 diabetics meeting inclusion criteria, 53.3% were female and 66.4% were white with a median hemoglobin A1c of 6.5%. Of the eligible enrollees, 166,696 (16.6%) were actively taking metformin and 296,498 (29.4%) had a history of metformin exposure. Over the study period, 29,831 (3.0%) eligible diabetics developed dAMD. After multivariable analysis, increasing age was associated with an increased hazard of developing dAMD (HR, 1.09; 95% CI, 1.09-1.09), as was non-proliferative diabetic retinopathy (HR, 1.19; 95% CI 1.15-1.23) and increased diabetes complications severity index score (HR, 1.03; 95% CI 1.03-1.04). Current metformin use among eligible diabetics was associated with an increased hazard of developing dAMD (HR, 1.08; 95% CI, 1.04-1.12) while prior metformin use had a decreased hazard (HR, 0.95; 95% CI, 0.92-0.98).
Conclusions :
In those with diabetes, small conflicting associations between exposure to metformin and development of dAMD were seen depending on whether medication use was active or historic. Thus, in this large national claims database, metformin exposure did not substantially effect the development of dAMD.
This is a 2020 ARVO Annual Meeting abstract.