Metformin linked to reduced risk of AMD in a diabetic population

This retrospective cross-sectional study examined the relationship between oral metformin use and development of AMD.

Study design

The authors used electronic medical records to identify all patients aged 60 years or older with a diagnosis of diabetes and who had an ophthalmology encounter between April 2012 and August 2019. The exposure variable of interest was metformin use prior to or at time of first ophthalmology visit. The outcome of interest was presence of AMD at the first encounter.

Outcomes

Of the 3,120 individuals with diabetes at their first ophthalmology encounter, 122 (3.9%) had non-neovascular AMD and 26 (0.8%) had neovascular AMD. Patients with documented metformin use were significantly less likely to have AMD (OR 0.7). The association was even stronger when looking at non-neovascular AMD alone (OR 0.59). None of the other common diabetes medications had a similar inverse correlation with AMD.

Limitations

The relatively small sample size and retrospective design are the main source of limitations. The study provides a correlation but no causal link. In addition, data collected from electronic medical records can be flawed and incomplete.

Clinical significance

In this study, metformin use was associated with a significantly reduced odds of AMD in a diabetic population.