Metformin Does Not Elevate AMD Risk in Newly Diagnosed Type 2 Diabetes

CHICAGO, ILLINOIS – JULY 09: In this photo illustration, Avkare metformin ER 500 mg tablets are shown on July 09, 2020 in Chicago, Illinois. Avkare and several other distributors are recalling the drug, which is used to treat people with type 2 diabetes, after high levels of N-nitrosodimethylamine (NDMA) impurities, a known carcinogen, have been found in the tablets. (Photo Illustration by Scott Olson/Getty Images)
Investigators say their findings suggest that high HbA1c may accelerate the development of AMD.

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