COVID-19 may increase a person’s risk of developing diabetes, a recent Canadian study found, but experts are still not sure exactly why this is.
The University of British Columbia study, published in JAMA on Tuesday, found that three to five per cent of diabetes cases were related to COVID-19 infection.
“From that point of view, these numbers are substantial,” Dr. Naveed Janjua, the study’s lead author, told Global News.
The study used provincial data and collected the health records of more than 620,000 people tested for COVID-19 from January 2020 to December 2021. The researchers then compared the data of those who tested positive (125,987) and negative (503,948) in order to see if the infection is associated with an increased risk of diabetes.
The UBC study found that for people who had diabetes during the studied timeframe, one out of 20 could have been related to their COVID-19 infection.
People infected with COVID-19 were 17 to 22 per cent at higher risk of developing diabetes within one year compared with those who were unexposed to the virus, the study stated.
Men were 22 per cent more likely than women to develop diabetes after a COVID-19 diagnosis, and people who were hospitalized with the virus had more than double the risk. For people who were admitted to the intensive care unit with COVID-19, their risk more than tripled, the study found.
Although a link was found between diabetes and COVID-19, the researchers said it’s not clear why.
“There are many possible explanations,” said Dr. Hertzel Gerstein, a professor and endocrinologist at McMaster University and deputy director of the Population Health Research Institute.
“One possibility could be that the COVID-19 virus might be affecting the pancreas, which makes insulin. And that is one of the ways that the body manages sugar levels and prevents it from getting diabetes,” he said.
Another reason could be that COVID-19 has been linked to an increased likelihood of getting sick, being hospitalized and seeing more doctors, he explained. As a result, that provides more opportunities to test for diabetes.
“I think we don’t know why. But in the end, we can always have theories,” Gerstein said. “The most important thing to know is that good research has shown that there is an increased incidence, it’s not a huge incidence, of getting diabetes if you had COVID.”
This isn’t the first study to find a connection between COVID-19 infection and diabetes. But the researchers stated previous research was conducted with “relatively small samples or have limitations related to participant selection or outcome ascertainment.”
A March 2022 study published in The Lancet, used the databases for the U.S. Department of Veterans Affairs and found during the post-acute phase of the disease, COVID-19 was significantly associated with an increased risk of incident diabetes.
Another study published in March 2022, looked at people who had COVID-19 in Germany and found they were 28 per cent more likely to have a new diagnosis of Type 2 diabetes compared with people who were never infected.
Diabetes on the rise in Canada
Diabetes has been on the rise in Canada over the last two-and-a-half decades, but it’s not clear why.
“About 25 years ago, it was closer to one in 20 people having diabetes and now we’re at one in 10,” Gerstein said, adding that the number goes up to one in five for people over the age of 65.
From 2015 to 2019, the number of Canadians diagnosed with diabetes went up around 20 per cent (from 2,077,300 to 2,495,100) especially among those over the age of 65, according to Statistics Canada.
The reasons for this diabetes epidemic are complex and there’s no clear answer, Gerstein said, but it may be a combination of genetics plus the environment.
And now it seems like COVID-19 is adding to the uptick in diabetes.
“I think COVID is adding to this burden,” said Gerstein, adding that although there may be a link, people still should not be “overly alarmed.”
“It’s just yet another example of how illnesses can increase the occurrence of other illnesses. And here’s an example of COVID-19, somehow promoting or increasing the occurrence of diabetes,” he said.
The findings of the study are important and mirror past studies, but Janjua said more research needs to be done in order to understand the potential link.
For example, for the people who developed diabetes during the study’s timeframe, Janjua said it is not known if the disease is permanent or whether it can resolve itself over a period of time.
Further studies will also “help us understand whether this is a real causation or it’s just an association,” he added.
He said it’s important for physicians and health-care providers to monitor people who had COVID-19 infections, in order to diagnose early and prevent complications of diabetes.
“And then we could also advise that people who had a COVID infection to take precautions related to diet and physical activity,” he added. “And that maybe that may reduce their risk of developing diabetes.”