People with diabetes undergoing treatment with metformin are at significantly less risk of dying from COVID-19 compared with those not taking the medication, researchers have said.
The study involved 25,326 people who underwent testing for COVID-19 at the University of Alabama at Birmingham (UAB) Hospital between February 25 and June 22, 2020.
Of those people who tested positive, 70% had hypertension, 61% had obesity and 40% had diabetes. Among those who had COVID-19, 11% died and in 93% of cases, the person who died was over the age of 50 years.
The researchers also found that being male and having hypertension were associated with an increased risk of death from COVID-19.
People with diabetes accounted for 67% of deaths, suggesting that this condition had a particularly significant effect on the risk of death.
But the people with diabetes who had been taking metformin had an 11% risk of dying, which was the same as that of the general population. In comparison, those with diabetes not taking metformin had a 24% risk of dying.
Lead researcher Professor Anath Shalev, director of the University of Alabama at Birmingham’s Comprehensive Diabetes Center, said: “This beneficial effect remained, even after correcting for age, sex, race, obesity, and hypertension or chronic kidney disease and heart failure.
“Since similar results have now been obtained in different populations from around the world — including China, France, and a [UnitedHealth] analysis — this suggests that the observed reduction in mortality risk associated with metformin use in subjects with type 2 diabetes and COVID-19 might be generalisable.”
The researchers could not confirm why metformin may be having these effects. As a diabetes treatment, it could be improving glycemic control or obesity.
However, among those with diabetes who took metformin, body mass index (BMI), blood glucose levels, and hemoglobin A1C levels were no higher in the people who died than in those who survived.
As a consequence, Professor Shalev thinks the “mechanisms may involve metformin’s previously described anti-inflammatory and antithrombotic effects”.
To further develop the findings, the researchers suggest that future research should look at why metformin may have this protective effect and the possible risks and benefits of prescribing the medication to protect against COVID-19.
The study, which has been published in the Frontiers in Endocrinology journal. Click here to read the research paper.