Key Takeaways

According to a new study,a medication frequently prescribed to treat type 2 diabetesmay reduce the risk oflong COVIDwhen taken during the acute phase of infection.

The medication, called metformin, was one of several medications researchers tested against long COVID in a phase 3 clinical trial called COVID-OUT.

The timing of treatment mattered, though; starting the two-week course of metformin less than four days after theonset of COVID symptomswas more effective than starting treatment four or more days after COVID symptoms started.The study focused on curbing long COVID risk during the acute phase of a COVID infection.

The study included over 1,100 people with COVID who had:

How Long COVID Looks and Feels

The study did not look at the effectiveness of metformin for preventing long COVID if the treatment was started while a patient was in the hospital. It also did not look at the effectiveness of the drug as a treatment for people who already had long COVID.

Why Metformin May Reduce Long COVID Risk

According to study authorDavid Liebovitz, MD, an internal medicine specialist at Northwestern Medicine, the exact way that metformin works against long COVID is still unknown.

One hypothesis is that metformin could directly target the SARS-CoV-2 virus. The study showed that starting metformin treatment earlier was linked to a stronger preventive effect against long COVID—not unlike how anantiviral treatmentwould work.

Other studies have suggested that the higher a person’s viral load is, the higher their risk for severe COVID symptoms and post-COVID symptoms.So using metformin to reduce the amount of virus in the body early on makes sense.

Liebovitz added that metformin is able to reduce oxidative stress on cells, as well as reduce inflammation. Previous research has identified the potential of repurposing metformin as a COVID treatment specifically for its antiviral and anti-inflammatory effects.

Researchers believe the drug may help quiet “cytokine storms,” the overproduction and uncontrolled release of pro-inflammatory cytokines that some researchers think could contribute to long COVID.

How Do You Know If You Have Long COVID?

Will Metformin Be Used to Try to Prevent Long COVID?

“It is possible this may change, or additional confirmatory studies may need to be published prior to its inclusion,” Liebovitz said.

If metformin becomes a COVID treatment drug, demand could increase and people who take it for these conditions could face shortages—though experts don’t think that’s a concern yet. Given the short course of metformin treatment as well as multiple manufacturers and formulations, Liebovitz said “a shortage would not appear likely for this widely available, safe, generic medication.”

Amesh Adalja, MD, an infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security, told Verywell that a shortage would be unlikely, but added that it will be important to assess supply chain resiliency should demand for metformin increase.

Could Any Medications We Already Have Help People With Long COVID?

Defining a Disease

The definition of long COVID evolved throughout the pandemic and healthcare providers and researchers still do not characterize the condition the same way.

Adalja said that not having a clear definition and diagnostic criteria “does hamper the development of treatments and preventatives” for long COVID, but that doing research while acknowledging the limitations is beneficial. That’s the only way to lead to new discoveries and a better understanding of the condition.

For the recent trial, the researchers used follow-up surveys to ask participants whether they had received a long COVID diagnosis on days 180, 210, 240, 270, and 300 after infection. This helped the researchers rule out other explanations for the patients’ lasting symptoms, which meetsthe World Health Organization’s definition of long COVID.

WHO Releases First Official Definition of Long COVID

The authors believe that the long follow-up and the way they identified long COVID cases based on the professional judgment and diagnosis of the participants’ providers would have helped address concerns about the differences in defining the condition.

Although emerging or newly-characterized conditions may have changing criteria for research, Liebovitz said the burden of a condition like long COVID is clear.

“The impact on patients’ lives and livelihoods is tremendous,” he said.

Many Americans are living with long-term symptoms, limited physical mobility, and impaired cognitive function after having COVID.Given the lasting “legacy” that COVID leaves, Liebovitz said that “making headway against this new scourge is of paramount importance.”

What This Means For YouNew research suggests that a diabetes drug called metformin may reduce the risk of long COVID, but it’s not yet approved as a treatment for the condition.

What This Means For You

New research suggests that a diabetes drug called metformin may reduce the risk of long COVID, but it’s not yet approved as a treatment for the condition.

How Can We Treat Long COVID?

9 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Bramante CT, Buse JB, Liebovitz DM, et al.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.Lancet Infect Dis. 2023;S1473-3099(23)00299-2. doi:10.1016/S1473-3099(23)00299-2

Bramante CT, Beckman KB, Mehta T, et al.Metformin reduces SARS-CoV-2 in a phase 3 randomized placebo controlled clinical trial.medRxiv. Preprint posted online June 6, 2023. doi:10.1101/2023.06.06.23290989

Girón Pérez DA, Fonseca-Agüero A, Toledo-Ibarra GA, et al.Post-COVID-19 syndrome in outpatients and its association with viral load.Int J Environ Res Public Health. 2022;19(22):15145. doi:10.3390/ijerph192215145.

Samuel SM, Varghese E, Büsselberg D.Therapeutic potential of metformin in COVID-19: reasoning for its protective role.Trends Microbiol. 2021;29(10):894-907. doi:10.1016/j.tim.2021.03.004

Montazersaheb S, Hosseiniyan Khatibi SM, Hejazi MS, et al.COVID-19 infection: an overview on cytokine storm and related interventions.Virol J. 2022;19:92. doi:10.1186/s12985-022-01814-1

Buonsenso D, Piazza M, Boner AL, et al.Long COVID: a proposed hypothesis-driven model of viral persistence for the pathophysiology of the syndrome.Allergy Asthma Proc. 2022;43(3):187-193. doi:10.2500/aap.2022.43.220018

Liu Y, Li J, Yan Z, Liu D, Ma J, Tong N.Improvement of insulin sensitivity increases pregnancy rate in infertile PCOS women: a systemic review.Front Endocrinol (Lausanne). 2021;12:657889. doi:10.3389/fendo.2021.657889

Blanchflower DG, Bryson A.Long COVID in the United States.NBER Work Pap Ser. 2023:30988. doi:10.3386/w30988

Meet Our Medical Expert Board

Share Feedback

Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit

Was this page helpful?

Thanks for your feedback!

What is your feedback?OtherHelpfulReport an ErrorSubmit

What is your feedback?