A study funded by the NIH found that “adults who use the prescription drug metformin to treat their type 2 diabetes have a lower risk of developing long COVID or dying after a COVID-19 infection than people with diabetes who take other anti-diabetes medications.”
Another NIH-supported clinical trial from 2023 showed that “treatment with metformin, commonly used to help control blood sugar, reduced the risk of long COVID by as much as 40% in nearly 1,300 U.S. adults” who were overweight or obese. The researchers for the new study then “compared health records from 75,996 adults taking metformin for their type 2 diabetes to 13,336 records from patients who were not taking metformin but were using other types of diabetes medicines. Researchers were specifically looking at how many patients either died or were diagnosed with long COVID within six months after infection. They found that patients taking metformin had a 13% to 21% lower incidence of long COVID or death than those in the non-metformin group.”
Scientists speculate that several mechanisms could be responsible for metformin seeming to prevent long COVID. These mechanisms “reduce inflammation, decrease viral levels, and suppress the formation of disease-related proteins.”