Patients receiving metformin treatment for type 2 diabetes were not at increased risk for age-related macular degeneration (AMD), according to results of a large, population-based retrospective study, published in the British Journal of Ophthalmology.
Patient records were extracted from IQVIA Medical Research Data, which is a national database of anonymized electronic primary care records from the United Kingdom. Between 1995 and 2019, patients (N = 173,689) who were initiating therapy for newly diagnosed type 2 diabetes were assessed for AMD risk on the basis of metformin use with or without other antidiabetic medications.
The patients were 57.1% men, aged mean 62.8 ± 11.6 years, 55.4% were obese, and 89% were on metformin. Stratified by gender, women were older, more had chronic kidney disease, fewer had cardiovascular disease, a higher proportion lived in more deprived Townsend quintiles, and fewer were smokers or former smokers.
During a mean follow-up of 5.7 years, 1.8% of patients developed AMD, occurring among more women (2.3%) than men (1.4%).
Risk for AMD was not associated with metformin (adjusted hazard ratio [aHR], 1.02; 95% CI, 0.92-1.12). These findings were not changed after accounting for duration of diabetes or glycated hemoglobin (HbA1c) levels.
Stratified by sex, the risk for AMD was higher among women (aHR, 1.39; 95% CI, 1.29-1.50). Additional risk factors included older age (aHR, 1.07; 95% CI, 1.7-1.7 per 1-year increase), current smoking (aHR, 1.14; 95% CI, 1.01-1.27), a history of smoking (aHR, 1.16; 95% CI, 1.07-1.26), and poor glycemic control (HbA1c >8.5%; aHR, 1.26; 95% CI, 1.07-1.48).
This study was limited by only including patients with type 2 diabetes. It remains unclear whether metformin alters risk for AMD among patients with type 1 diabetes.
The study authors found that metformin did not increase risk for AMD among patients with newly diagnosed type 2 diabetes. Risk for AMD was linked with sex, age, smoking status, and glycemic control.
Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.
Gokhale KM, Adderley NJ, Subramanian A, et al. Metformin and risk of age-related macular degeneration in individuals with type 2 diabetes: a retrospective cohort study. Br J Ophthalmol. Published online February 3, 2022. doi:10.1136/bjophthalmol-2021-319641