Metformin — a popular oral medication used to treat type 2 diabetes — has been characterized by some as an anti-aging drug because of its ability to mimic the physiological effects of reduced calorie intake. Previous studies have shown that it can delay or reduce the risk of age-associated diseases such as cancer and cardiovascular disease. However, its effect on age-associated eye disease is largely unknown — until now. New research published online in JAMA Ophthalmology shows that metformin use is indeed associated with a reduced risk of open-angle glaucoma.
For this study, a multidisciplinary team from the University of Michigan and Indiana University collected 10 years of data from more than 150,000 people with diabetes who were 40 years of age or older. The researchers found that those who were prescribed the largest doses of metformin (more than 1,110 grams total over 2 years) had a 25 percent reduced risk of glaucoma compared with those not taking the drug at all. They also found that for every 1-gram increase in the dosage, glaucoma risk was reduced by 0.16 percent. Based on these results, the researchers predicted that taking a standard 2-gram prescription of the medication daily for 2 years could reduce the risk of glaucoma by 20 percent.
These risk reductions held true even after adjusting the analysis for the lowered blood sugar levels induced by metformin. Other diabetes medications, such as insulin, did not have the same effect on risk reduction.
According to the study authors, the exact mechanisms by which metformin reduces the risk of open-angle glaucoma are not currently known. In addition, people who don’t have diabetes should not be taking metformin because of the possibility of adverse side effects and low blood sugar. Nevertheless, future clinical trials replicating these findings in patients without diabetes could lead to new treatment options for a disease that affects more than 60 million individuals worldwide.