Of the people who tested positive for COVID-19, 70% had hypertension, 61% had obesity, and 40% had diabetes.
Of the patients who tested positive for COVID-19, 11% died. 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.
The researchers then analyzed the data to account for potential covariates that may affect other risk factors. They identified age, sex, and diabetes as key independent risk factors for death due to COVID-19.
Finally, the researchers looked in more detail at the people with diabetes. They found that those who tested positive who were taking metformin — a medication that doctors use to treat diabetes — 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.
Prof. Shalev notes, “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 generalizable.”
– Prof. Anath Shalev
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, Prof. Shalev suggests that “[t]he 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.
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