Photo of two hands held palm up with the left one holding a positive COVID-19 antigen test and the other holding a blood glucose monitor with a test strip inserted showing a reading of 126 to indicate the diabetes risks linked to SARS-CoV-2 infection.
Credit: Ake Ngiamsanguan/Getty Images

Results from a large Canadian study suggest that infection with the SARS-CoV-2 virus increases a person’s risk for developing diabetes by a small but significant percentage.

Writing in the journal JAMA Network Open, Naveed Janjua, PhD, a professor at the University of British Columbia and executive director of data and analytic services at the British Columbia Centre for Disease Control, and colleagues report that 3–5% of incident diabetes cases in the study could be attributed to COVID-19.

Since the beginning of the pandemic, it has become clear that SARS-CoV-2 infection can leave those infected with a range of different long-term adverse outcomes. In addition to a significant percentage of people experiencing long-term symptoms or “long COVID,” some also appear to be at increased risk for cardiovascular, neurological, and metabolic conditions including diabetes.

“Diabetes has already been established as a risk factor associated with more severe COVID-19 respiratory outcomes, and SARS-CoV-2 infection was associated with the worsening of pre-existing diabetes symptoms,” the authors wrote.

“However, it is not fully known if SARS-CoV-2 infection is associated with transient hyperglycemia during active infection or if metabolic alterations persist, associated with increased risk of subsequent diabetes among individuals with infections.”

This study was a population-based cohort study carried out between 2020 and 2021 in British Columbia, Canada, among individuals enrolled in the British Columbia COVID-19 Cohort, “a platform that integrates COVID-19 data with population-based registries and administrative data sets.”

The outcome measure in the study was incident diabetes (either type 1 or type 2) identified at least 30 days after a positive SARS-CoV-2 test.

Overall, 629,935 individuals were included. Of these, 125,987 were exposed and 503,948 were unexposed to the virus. Over 102–356 days of follow-up, 0.5% of 608 exposed participants developed diabetes vs 0.4% of 1864 who were not exposed.

Being exposed to SARS-CoV-2 infection increased the risk of incident diabetes in the follow-up period by 17% compared with those who were not exposed. Males had an increased risk and those who were exposed had a 22% increase in risk vs those who were not.

Having severe COVID-19 that required hospital admission or a stay in an intensive care unit increased the risk of subsequent diabetes substantially by 2.4- and 3.3-fold, respectively, compared with uninfected individuals.

After taking possible confounders and other factors into account, the researchers estimated that 3.4% of incident diabetes cases in the group were attributable to SARS-CoV-2 infection overall and 4.8% of cases in males.

“These findings suggest that COVID-19 infection may continue to be associated with outcomes in organ systems involved in regulating blood glucose in the post-acute phase and so may have contributed to the 3% to 5% of excess incident diabetes cases found in this study,” the authors wrote.

They added, “Our overall results were consistent with several other studies finding higher risk of incident diabetes after SARS-CoV-2 infection; however, the increase in risk was lower in our analysis compared with other studies,” which they think was due to demographically diverse nature of the cohort used in this study in terms of age, sex, and ethnicity. The rate of obesity, a factor associated with both adverse COVID-19 outcomes and diabetes, was also relatively low in the Canadian cohort.

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