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Long COVID Risk Reduced by Common Diabetes Drug

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Metformin, a drug commonly used to treat diabetes, can reduce the risk of developing long COVID by over 40%, according to a study published in The Lancet Infectious Diseases.


There are currently no drugs available to treat long COVID; however, this chronic – and possibly debilitating – condition can affect up to 10% of people who have had COVID-19.

In the current study, researchers from the University of Minnesota (UMN) and the University of North Carolina set out to investigate metformin as a possible preventative measure after its success in stopping the virus was predicted by a simulator. “Long COVID is an important public health emergency that might have lasting health, mental health, and economic sequelae, particularly in socioeconomically marginalised groups,” the authors write.

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The study, called COVID-OUT, was a placebo-controlled Phase III clinical trial conducted at six sites in the US. Those recruited to the trial were overweight or obese, aged 30–85 years and had symptoms of COVID-19 for less than a week and a positive PCR or antigen test within three days of enrolment.

The trial investigated the ability of three different medications (metformin, ivermectin and fluvoxamine) to reduce the risk of long COVID when administered during acute infection.

Upon trial opening, participants were randomly assigned to either metformin or placebo. After this, participants were randomly assigned to receive metformin plus ivermectin, placebo plus ivermectin, metformin plus fluvoxamine, placebo plus fluvoxamine, metformin plus placebo or placebo plus placebo.

Neither ivermectin nor fluvoxamine were seen to reduce the risk of the chronic condition.

Prevention over treatment

At a 10-month follow-up, 6.3% of people who received metformin had developed long COVID, compared with 10.4% of those who took a placebo. This represents a 41% lower risk of long COVID for patients who received metformin.

In participants who started metformin less than four days after their symptoms began, the risk of developing long COVID was decreased by 63%.

“Metformin is an inexpensive, safe and widely available drug, and its use as a preventive measure could have significant public health implications,” says Carolyn Bramante, MD, principal investigator and an assistant professor at UNM Medical School. “This long-term outcome from a randomized trial is high-quality evidence that metformin prevents harm from the SARS-CoV-2 virus.”

According to Bramante, further research could show whether metformin is also effective in those with previous infection or in adults with lower body mass index: “while half of our trial had been vaccinated, none had been previously infected with the COVID-19 virus.”

Reference: 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;0(0). doi: 10.1016/S1473-3099(23)00299-2

This article is a rework of a press release issued by UNC School of Medicine. Material has been edited for length and content.