Metformin, a treatment for type 2 diabetes, reduced the risk of Long COVID by about 41% in a study of more than 1,100 people.

Metformin, a treatment for type 2 diabetes, reduced the risk of Long COVID by about 41% in a study of more than 1,100 people.

What you need to know

When someone is infected with SARS-CoV-2, the virus that causes COVID-19, they are at risk of developing Long COVID, symptoms that linger for weeks, months, or even longer after their initial diagnosis. Being of older age and having certain health conditions, like overweight or obesity, can increase a person’s risk of developing Long COVID.

Some studies suggest that metformin, a common treatment for type 2 diabetes, may reduce the risk of severe COVID-19 for patients receiving the treatment as part of their care.

In a study supported by the Researching COVID to Enhance Recovery (RECOVER) Initiative, researchers assessed the effect of metformin on people’s risk of developing Long COVID. The results suggest that metformin may provide protection against Long COVID.

What did the researchers do?

Between 2020 and 2022, the researchers enrolled more than 1,400 people with COVID-19 in a clinical trial; participants were between ages 30 and 85 and had overweight or obesity. The study also included participants who were pregnant or lactating, which is another risk factor for severe COVID-19.

Half of the study participants received metformin and half did not. Participants took the experimental treatment for 6 days, then received surveys each month for up to 10 months asking about their recovery and any lingering symptoms.

Of the 1,400 participants, 1,126 completed the follow-up surveys. Among people who received metformin, 35 (6.2%) had received a Long COVID diagnosis by the 10-month survey. Among those who did not receive metformin, 58 (10.3%) were diagnosed with Long COVID, meaning that metformin was associated with a Long COVID risk reduction of more than 40%.

Why is this research important?

Because certain groups have a greater risk of developing Long COVID, finding treatments to reduce their risk of the condition is valuable. Metformin has already been shown to be safe, and it is widely available at low cost, making it a potentially powerful tool in the fight against Long COVID.

This study began before the widespread distribution of vaccines, so future research can determine whether metformin helps prevent Long COVID in people who have been vaccinated against COVID-19 or in people who have had COVID-19 before. Research suggests that people who are vaccinated against COVID-19 are less likely to develop Long COVID.

Where can I go to learn more?

Large Study Allows Researchers to Better Define Long COVID

  • Researchers supported by NIH created a symptom-based scoring system to identify people with Long COVID.

Study Looks for Long COVID Risk Factors

  • Researchers have identified factors that are associated with an increased risk of Long COVID.

Guidance on Long COVID as a Disability Under the ADA

  • The U.S. Department of Health and Human Services provides information on resources for people with symptoms of Long COVID that cause physical or mental impairment.


Bramante, C. T., Buse, J. B., Liebovitz, D. M., Nicklas, J. M., Puskarich, M. A., Cohen, K., Belani, H. K., Anderson, B. J., Huling, J. D., Tignanelli, C. J., Thompson, J. L., Pullen, M., Wirtz, E. L., Siegel, L. K., Proper, J. L., Odde, D. J., Klatt, N. R., Sherwood, N. E., Lindberg, S. M., & Boulware, D. R. (2023). Outpatient treatment of COVID-19 and incidence of post-COVID-19 condition over 10 months (COVID-OUT): A multicentre, randomised, quadruple-blind, parallel-group, phase 3 trial. The Lancet Infectious Diseases.


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Page last updated: August 1, 2023