Common diabetes drug lowers SARS-CoV-2 levels, clinical trial finds

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Today, researchers from the University of Minnesota published evidence that the common diabetes drug metformin decreases the amount of SARS-CoV-2 in the body and helps reduce the risk of rebound symptoms if given early in the course of non-severe illness. 

The study, published in Clinical Infectious Diseases, suggests metformin may also help prevent long COVID.

The researchers tested metformin against a placebo in 999 adults infected with COVID-19. More than 50% of the study enrollees were vaccinated, and treatment took place when the Omicron variant was the most dominant strain in the United States. 

Study included those at standard-risk 

Moreover, according to Carolyn Bramante, MD, principal investigator of the study and an assistant professor at the University of Minnesota, the study participants represented a standard- risk population, a group that currently lacks effective treatment options for the novel coronavirus.

"This is not a high-risk population," Bramante told CIDRAP News. Instead, participants were 30 years or older, had a body mass index of 25 or higher (overweight), and did not require hospitalization for their COVID-19 infection. 

In several trials, Paxlovid has been shown to prevent deaths and hospitalization in high-risk, unvaccinated people, but standard-risk populations have not shown improvement in either time to resolution of symptoms or the incidence of hospitalization or death.

Bramante said that these patient population demographics suggest metformin may be a clinical tool in outpatient medication that could be widely used.

"The data support that someone would be justified if they prescribed it for outpatient treatment," she said. 

Four-fold reduction in viral load by day 10

Participants were given a 14-day course of metformin, and participants collected nasal swabs on days 1, 5, and 10. Bramante said early treatment was key: Participants were enrolled within 3 days of a positive test, and if symptomatic, reported having symptoms for 7 or fewer days.

The mean SARS-CoV-2 viral load was reduced 3.6-fold with metformin relative to placebo by day 10, the authors found, and those who received metformin were less likely to have a detectable viral load than placebo at days 5 or 10 (odds ratio [OR], 0.72; 95% confidence interval [CI], 0.55 to 0.94).

Metformin reduced the odds of hospitalization or death through 28 days by 58%; emergency department visits, hospitalizations, and death through 14 days by 42%; and long COVID through 10 months by 42%.

Viral rebound, defined as a higher viral load at day 10 than day 5, was less frequent with metformin (3.28%) than placebo (5.95%; OR, 0.68; 95% CI, 0.36 to 1.29).

While the mechanism of action is not known, Bramante said metformin likely lowers inflammation and inhibits translation of the virus. 

This study makes a strong case for a potential effect of metformin on COVID-19 virologic decay.

In a commentary on the study, the authors write, "This study makes a strong case for a potential effect of metformin on COVID-19 virologic decay and prompts reevaluation of existing data in support of its use."