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Disclosures: The authors report no relevant financial disclosures.
February 03, 2021
2 min read

COVID-19 mortality odds lower for metformin users with diabetes

Disclosures: The authors report no relevant financial disclosures.
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Prior use of metformin was associated with a threefold decrease in COVID-19 mortality for people with diabetes independent of glucose profile and BMI, according to study data.

“It was a surprise to us to see such a significant decrease in mortality linked to prior use of metformin, even after all of the adjustments, and to find that these beneficial effects were not linked to any improvement in glycemic control or obesity — blood glucose, HbA1c or BMI were not lower in COVID-19 survivors,” Anath Shalev, MD, professor of medicine and director of the Comprehensive Diabetes Center at the University of Alabama at Birmingham, told Healio. “Also, subjects not taking metformin did not have more severe metabolic disease or diabetes than those on metformin as demonstrated by comparable or even lower BMI and HbA1c values, suggesting that other mechanisms were responsible for these protective effects.”

Shalev is a professor of medicine and director of the Comprehensive Diabetes Center at the University of Alabama at Birmingham.

Shalev and colleagues conducted a retrospective review of over 25,000 electronic health records, including 604 people who tested positive for COVID-19, at the University of Alabama at Birmingham between Feb. 25 and June 22, 2020. Researchers collected data on patient characteristics and comorbidities. Metformin and insulin were the two diabetes medications analyzed in the study. The study’s findings were published in Frontiers in Endocrinology.

Of the study population that tested positive for COVID-19, 52% were Black even though Blacks represent only 26% of the population in Alabama, and 36% were white, underscoring the racial disparity of this pandemic. There was preexisting hypertension in 70% of the COVID-19 positive study population, 61% had obesity and 40% had diabetes. Those with diabetes who tested positive for COVID-19 had higher odds for mortality (OR = 3.62; 95% CI, 2.11-6.2; P < .0001), and 67% of all deaths occurred in people with diabetes. In addition to diabetes, older age and male sex were associated with an increased risk for mortality, and no difference was observed between type 1 and type 2 diabetes.

Researchers analyzed patients’ use of insulin and metformin prior to testing positive for COVID-19. Metformin was found to decrease the odds of COVID-19 mortality (OR = 0.38; 95% CI, 0.17-0.87; P = .0221) while insulin did not affect the mortality rate. Of those who used metformin, the morality rate was 11%, which was comparable to the general population mortality rate and less than half of the 24% mortality rate among people with diabetes who did not use metformin.

The association between metformin use and reduced COVID-19 mortality odds remained after those with chronic kidney disease or chronic heart failure were excluded (OR = 0.17; 95% CI, 0.04-0.79; P = .0231). Mortality odds were also lower for men on metformin (OR = 0.28; 95% CI, 0.09-0.88; P = .0286). After adjusting for age, sex, ethnicity, insulin use, obesity and hypertension, those who took metformin had a lower likelihood for mortality than those who did not take metformin (OR = 0.33; 95% CI, 0.13-0.84; P = .021).

“Now more than ever, it is important to follow general diabetes treatment guidelines and not to delay or discontinue any metformin treatment of individuals with type 2 diabetes,” Shalev said. “Especially during this pandemic that puts subjects with diabetes at particularly high risk, this treatment might not only help with diabetes management, but also reduce the risk of adverse outcome in case of a COVID-19 infection.”

For more information:

Anath Shalev, MD, can be reached at