The diabetes drug metformin could prevent long covid, but whether it can also treat the condition in people who already have it is unclear.
An estimated 65 million people worldwide have some degree of long covid, which can involve chronic fatigue, brain fog, heart and lung problems, and loss of taste and smell, among other issues.
With preventative drugs and other treatment options being limited, Carolyn Bramante at the University of Minnesota and her colleagues tested the potential of several therapies, including metformin, which is commonly used to control blood sugar levels in people with type 2 diabetes and has been shown to limit the replication of the SARS-CoV-2 coronavirus in the lab.
The team looked at 1126 people, aged 30 to 85, who had tested positive for SARS-CoV-2 within the past three days. They were all overweight or obese, which can raise the risk of severe covid-19, but they didn’t require hospital care for the infection.
The participants were randomised to receive a range of potential treatments, including combinations of metformin, the anti-parasitic drug ivermectin, the antidepressant fluvoxamine or a placebo. At a 10-month follow-up, 6.3 per cent of those who took metformin had been diagnosed with long covid, compared with 10.4 per cent on placebo, suggesting that the drug prevented 41 per cent of long covid cases in the trial. Neither ivermectin nor fluvoxamine reduced the risk.
While metformin may prevent long covid among people who are overweight or obese and who have a mild SARS-CoV-2 infection, the drug’s potential in other groups, or as a long covid treatment, is unclear.
Grace McComsey, who leads the long covid RECOVER study at University Hospitals Health System in Cleveland, Ohio, says the latest research is encouraging. “A 40 per cent decrease is pretty impressive, especially considering that most of the study population was fully vaccinated and already at a lower risk of getting long covid,” she says.
Metformin may work as both an anti-inflammatory and by reducing SARS-CoV-2’s viral load in an infected person’s body, she says. If it is an antiviral, metformin “could potentially work for the treatment of those with long covid”, says McComsey.