Metformin Reduces Risk of Long COVID

New research found that metformin, a medication that helps control blood sugar in people with type 2 diabetes, may also prevent long COVID if taken shortly after COVID-19 symptoms begin.

To conduct the randomized, quadruple-blind, phase 3 trial, published on June 8 in The Lancet Infectious Diseases, researchers included overweight or obese adults aged 30 to 85 years who were experiencing COVID-19 symptoms for less than seven days. The researchers also included pregnant women in the trial.

In addition, the participants had a positive SARS-CoV-2 PCR or antigen test within three days before enrolling in the study.

From December 2020 to January 2022, 1,126 participants who met enrollment requirements received one of six drug combinations. These included metformin with either ivermectin, fluvoxamine, or a placebo, or a placebo with either ivermectin, fluvoxamine, or another placebo.

After a 10-month follow-up, the scientists found that 6.3% of participants who received metformin within three days of testing positive for COVID had a long COVID diagnosis at ten months. In contrast, 10.4% of those who took a placebo were diagnosed with long COVID.

The scientists suggest that, in the trial, metformin prevented over 40% of long COVID cases.

However, ivermectin and fluvoxamine did not appear to prevent long COVID.

While the study did have some limitations, such as it excluded people younger than 30 and those with a body mass index (BMI) under 25, it is the first randomized control trial published that suggests taking medication during the early phase of COVID-19 may reduce the risk of long COVID.

In an article accompanying the study, Jeremy Faust from the Department of Emergency Medicine, Brigham and Woman's Hospital and Harvard Medical School writes, "If confirmed, the findings from the study by Bramante and colleagues are profound. […] To our knowledge, this is the first high-quality evidence from a randomized controlled trial to show that the incidence of long COVID can be reduced by a medical intervention, metformin — an inexpensive treatment with which clinicians have ample experience."

According to the study authors, people with long COVID often need ongoing medical treatment or are unable to perform work duties for six months or longer.

Therefore, they say these findings indicate that "implementing metformin as a COVID-19 treatment to prevent long COVID is an urgent public health need."