Oral Metformin Therapy Mitigates AMD Risk in 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 suggest the drug may play a role in preventing disease progression.

Oral metformin therapy may reduce the risk for age-related macular degeneration (AMD) in people with diabetes, according to research published in Ophthalmology Retina. 

Researchers conducted a retrospective, cross-sectional study of patients with diabetes to assess the relationship between metformin use and AMD. An electronic medical record extraction identified 3120 adults aged 60 or older with diabetes at the time of their first ophthalmology encounter. 

Of these patients, 3.9% had non-neovascular AMD; 0.8% had neovascular AMD recorded at their first ophthalmology visit. Those with documented use of metformin therapy were significantly less likely to have AMD (odds ratio [OR], 0.70; 95% CI, 0.55-0.88). No other commonly used diabetes medications demonstrated a strong inverse correlation with AMD development. 

When adjusted for race, the relationship between metformin use and AMD was not significantly changed (P =.44 for White vs non-White patients). Some evidence demonstrated a weaker association among patients classified as either current or former vs never smokers or those with unknown smoking status (OR, 0.92; 95% CI, 0.64-1.31 vs OR, 0.56; 95% CI, 0.41-0.77). 

A sensitivity analysis of patients taking 1 or more diabetes medication (n=2642) demonstrated consistent results (OR, 0.63; 95% CI, 0.49-0.82).

Limitations to this study include the retrospective design, the reliance on data entered into the medical record, and the relatively small sample size. Because the study was observational, conclusions about causality could not be made. 

“Given the current lack of effective therapies for non-neovascular AMD, this study adds to the body of evidence supporting further evaluation of metformin as an intervention for AMD in larger populations and possibly in future prospective trials,” the researchers concluded. 


Stewart JM, Lamy R, Wu F, Keenan JD. Relationship between oral metformin use and age-related macular degeneration. Ophthalmol Retina. 2020;4(11):1118-1119.