Newswise — MINNEAPOLIS/ST. PAUL (06/09/2023) —According to a recent publication in The Lancet Infectious Diseases, a team of researchers from the University of Minnesota has discovered that metformin, a widely prescribed medication for diabetes management, can effectively inhibit the onset of long COVID.

The COVID-OUT study, conducted to explore the potential of early outpatient treatment for COVID-19, examined the effectiveness of metformin, ivermectin, and fluvoxamine in preventing the development of long COVID. Long COVID is a persistent condition that can impact around 10% of individuals who have previously contracted COVID-19.

"The findings of this research hold great significance as long COVID can profoundly affect individuals' quality of life," stated Dr. Carolyn Bramante, the principal investigator and an assistant professor at the University of Minnesota Medical School. Dr. Bramante further emphasized, "Metformin, being an affordable, safe, and easily accessible medication, carries substantial public health implications if utilized as a preventive measure."

Conducted as a substantial placebo-controlled randomized clinical trial encompassing participants from various regions in the United States, the study yielded the following notable outcomes:

  1. Individuals administered with metformin displayed a reduction of over 40% in the likelihood of developing long COVID compared to those given an indistinguishable placebo.
  2. Among participants who initiated metformin within four days of experiencing COVID symptoms, the risk of long COVID decreased by an impressive 63%.
  3. The observed effects of metformin remained consistent across diverse demographic groups of volunteers and in the face of various viral variants, including the Omicron variant.
  4. Conversely, the study revealed that ivermectin and fluvoxamine did not exhibit preventive properties against long COVID.

The study included more than 1,200 participants who were randomly chosen to receive either metformin or placebo, and an additional subset received ivermectin, fluvoxamine or their placebos. Participants were between 30 and 85 years old who qualified as overweight or obese. Over 1,100 of the participants reported on their symptoms for up to 10 months after their initial COVID-19 diagnosis.

Dr. Bramante, who serves as an internist, pediatrician at M Health Fairview, and the principal investigator, stated, "This randomized trial's long-term outcomes provide robust evidence that metformin effectively mitigates harm caused by the SARS-CoV-2 virus." She further added, "Although half of our trial participants were vaccinated, none of them had prior COVID-19 infections. Further investigation is needed to determine whether metformin remains efficacious in individuals with previous infections or in adults with lower body mass index."

The effectiveness of metformin in inhibiting the virus was anticipated through the utilization of a simulator developed by the faculty of U of M Medical School and College of Science and Engineering Biomedical Engineering. This model has demonstrated remarkable accuracy thus far, accurately predicting various outcomes, including the inefficacy of hydroxychloroquine and the success of remdesivir, even before the results of clinical trials evaluating these treatments were announced.

The research received funding from multiple sources including the Parsemus Foundation, Rainwater Charitable Foundation, Fast Grants, and the United Health Foundation. Additionally, support for this study was provided by the National Institutes of Health's National Center for Advancing Translational Sciences under award numbers UL1TR002494, KL2TR002492, and UM1TR004406.

The University of Minnesota Medical School, School of Public Health, College of Science and Engineering, and M Health Fairview played a central role as the lead site in conducting the trial. Additionally, the trial was carried out in collaboration with other esteemed institutions including Northwestern University, University of Colorado, Denver, Olive View - UCLA Education & Research Institute in Los Angeles, and Optum Health. Furthermore, scientific collaboration was established with partners from the University of North Carolina at Chapel Hill, Vanderbilt University, and Emory University School of Medicine.

The authors of this study bear full responsibility for its content, and the views expressed therein do not necessarily reflect the official stance of the National Institutes of Health's National Center for Advancing Translational Sciences.

About the University of Minnesota Medical School
The University of Minnesota Medical School is at the forefront of learning and discovery, transforming medical care and educating the next generation of physicians. Our graduates and faculty produce high-impact biomedical research and advance the practice of medicine. We acknowledge that the U of M Medical School, both the Twin Cities campus and Duluth campus, is located on traditional, ancestral and contemporary lands of the Dakota and the Ojibwe, and scores of other Indigenous people, and we affirm our commitment to tribal communities and their sovereignty as we seek to improve and strengthen our relations with tribal nations. For more information about the U of M Medical School, please visit

Journal Link: The Lancet Infectious Diseases