Prior Metformin Use Reduces COVID-19 Mortality Risk in Patients With Diabetes


A recent study examined patient characteristics and factors affecting COVID-19 mortality in individuals with diabetes.


Results of a recent study suggest that taking metformin prior to coronavirus disease 2019 (COVID-19) diagnosis reduced mortality in individuals with type 2 diabetes.1

Diabetes is a significant risk factor for COVID-19–related mortality. The study, published in Frontiers in Endocrinology, included 25,326 patients tested for COVID-19 at the tertiary care University of Alabama at Birmingham (UAB) Hospital between February 25 and June 22 of last year. The investigators aimed to identify the patient characteristics and factors affecting mortality, particularly in the context of diabetes, in a diverse cohort.1

Using electronic health record (EHR) data, the study investigators analyzed mortality in COVID-19–positive patients and the association with characteristics and comorbidities. The findings demonstrated disproportionately high odds of contracting COVID-19 among Black and African American patients, as well as in individuals with obesity, hypertension, and diabetes. Fifty-percent of those who tested positive for COVID-19 were Black, whereas 36% were white.1

“In our cohort, being African American appeared to be primarily a risk factor for contracting COVID-19, rather than for mortality,” lead study author Anath Shalev, MD, director of UAB’s Comprehensive Diabetes Center, said.2 “This suggests that any racial disparity observed is likely due to exposure risk and external socioeconomic factors, including access to proper health care.”

The investigators reported a dramatic increase in mortality in those with diabetes (OR 3.62; 95% CI 2.11-6.2; p<.0001). Even after correcting for age, race, sex, obesity, and hypertension, diabetes emerged as an independent risk factor in the study population, the investigators wrote.1

Moreover, investigators reported that metformin treatment prior to COVID-19 diagnosis was independently associated with a 3-fold decrease in mortality in patients with diabetes and COVID-19 (OR .33; 95% CI .13-.84; p=.0210).1

According to the data, metformin users with COVID-19 demonstrated an 11% mortality, which was comparable to that of the general COVID-19–positive population and drastically lower than the 32% mortality for patients with diabetes not on metformin.1

Shalev also noted that just how metformin appears to improve COVID-19 progress in these patients is not known. Interestingly, neither body mass index, blood glucose, nor hemoglobin A1C were lower in metformin users who survived compared with those who died.2

“The mechanisms may involve metformin’s previously described anti-inflammatory and anti-thrombotic effects,” Shalev said.2

According to the investigators, limitations of the study include the size that did not allow for separate analyses of additional subgroups such as type 1 diabetes or individual on other anti-diabetic drugs besides metformin.1

Future studies will need to explore how metformin might confer these protective effects, provide a careful risk benefit assessment, and determine whether the indications for metformin treatment should be broadened amid the pandemic, the investigators concluded.1

The study is part of a new Precision Diabetes Program, a collaboration between UAB Comprehensive Diabetes Center and the Hugh Kaul Precision Medicine Institute at UAB.2


  1. Crouse AB, Grimes T, Li P, et al. Metformin use is associated with reduced mortality in a diverse population with COVID-19 and diabetes. Frontiers in Endocrinology. 2021.
  2. Metformin use reduces risk of death for patients with COVID-19 and diabetes. News release. The University of Alabama at Birmingham; January 14, 2021. Accessed January 26, 2021.

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