The anti-diabetic drug metformin, when taken at the time of Covid-19 infection, could reduce the rate of long Covid-19, a new study found.

In the Phase III COVID-OUT study (NCT04510194), patients who used metformin at the time of Covid-19 infection had a 41% reduction in long Covid rates. The study results shed light on a potential preventive treatment for a condition that clinicians have struggled to treat effectively.

During the COVID-OUT study, investigators tested three generic drugs— metformin, fluvoxamine, and ivermectin—as outpatient treatments for 1,350 patients with acute Covid-19. The patients were then followed for around nine additional months to monitor for long Covid symptoms.

Long Covid, also known as post-acute sequelae of Covid-19 (PASC), describes the persistent symptoms that can occur after an acute Covid-19 infection. These can include shortness of breath, fatigue, brain fog, and an array of other respiratory and cognitive symptoms.

Despite significant drug development activity, researchers have thus far had only limited success in developing treatments for long Covid.

Metformin and long Covid

Metformin, an anti-inflammatory agent normally used to lower blood sugar, is taken by approximately 150 million people worldwide. Given the generic drug’s low cost and widespread use, researchers are hopeful it could provide an affordable preventive measure for long Covid.

In the COVID-OUT study, patients receiving metformin at the time of infection also had a 42% reduction in emergency room visits, hospitalisations, or death. This suggests the drug could also work as an effective outpatient treatment.

Researchers said metformin could also provide a potential alternative to Pfizer’s oral Covid-19 antiviral Paxlovid (nirmatrelvir + ritonavir). Though Paxlovid is widely considered the standard of care, approximately one in three people cannot take the antiviral due to potential cross-interactions.