A widely prescribed Type 2 diabetes medication, metformin, has been linked to a 39% lower risk of death within 12 months after COVID-19 infection, according to a study involving more than 53,000 patients in the United States, raising new interest in the drug’s potential benefits beyond blood sugar control.
Published in the journal Diabetes, Obesity and Metabolism, the study was led by researchers from Stanford University and examined health records of 53,332 adults with Type 2 diabetes who contracted COVID-19 between October 2021 and November 2023.
Researchers compared patients prescribed metformin with those taking dipeptidyl peptidase-4 inhibitors, or DPP-4 inhibitors, another class of diabetes medication. Of the participants, 50,965 had been prescribed metformin, while 2,367 were taking DPP-4 inhibitors.
The analysis found that metformin use was associated with a 39% lower risk of all-cause mortality over the following 12 months. Researchers also observed a modest reduction in the risk of probable long COVID, although the difference was not statistically significant for formally diagnosed long COVID.
Metformin is commonly prescribed to manage Type 2 diabetes. It works primarily by reducing glucose production in the liver and improving the body’s sensitivity to insulin. Researchers believe its anti-inflammatory and other biological effects may also play a role in the outcomes observed among COVID-19 patients.
The findings add to growing research into the possible use of metformin against complications of COVID-19. In June 2026, a separate University of Minnesota-led randomized clinical trial involving nearly 3,000 adults found that participants given metformin during acute COVID-19 infection had a 50% lower relative risk of receiving a clinical diagnosis of long COVID after six months compared with those given a placebo.
That trial, conducted through the ACTIV-6 research program, provided additional evidence of a possible benefit, although its primary outcome of reducing persistent COVID-19 symptoms did not meet the study’s prespecified threshold for efficacy.
The Stanford study, however, was observational and relied on existing medical records. It therefore cannot establish that metformin itself caused the lower mortality risk. Differences in patients’ age, underlying health conditions and other factors may have influenced the results.
Metformin has been used in diabetes treatment for decades. First introduced for clinical diabetes management in 1957 by French physician Jean Sterne, it became one of the most widely prescribed medications for Type 2 diabetes and received approval for use in the United States in 1995.
Researchers say further studies are needed to establish how metformin may influence COVID-19 outcomes and whether its potential benefits extend to other patient groups.
The findings do not mean metformin should be taken to prevent or treat COVID-19 without medical supervision. Patients taking the medication for diabetes should continue following their prescribed treatment and consult their healthcare providers before making any changes.
Edgardo Hernal started college at UP Diliman and received his BA in Economics from San Sebastian College, Manila, and Masters in Information Systems Management from Keller Graduate School of Management of DeVry University in Oak Brook, IL. He has 25 years of copy editing and management experience at Thomson West, a subsidiary of Thomson Reuters.
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