The link between COVID-19 and diabetes

According to Nature, researchers first voiced concerns that COVID-19 may be associated with type 1 diabetes in the early months of the pandemic after an increase in new cases was observed in several countries. Since then, there has been other evidence to suggest that diabetes diagnoses rose significantly after COVID-19 peaked.

For example, investigators from the Smidt Heart Institute at Cedar-Sinai in February reported that individuals who had COVID-19 had a higher risk of developing new-onset diabetes. In the study, researchers evaluated medical records from 23,709 adult patients who had at least one COVID-19 infection and were treated at Cedars-Sinai between 2020 and 2022.

In adjusted models, the researchers found that a history of COVID-19 infection was associated with a 58% increased risk of developing new-onset diabetes compared to another benchmark condition. This risk was even higher among unvaccinated patients, who had a 78% increased risk of developing diabetes within 90 days of their initial infection.

"Our results validate early findings revealing a risk of developing Type 2 diabetes after a COVID-19 infection and indicate that this risk has, unfortunately, persisted through the Omicron era," said Alan Kwan, the study's first author and a cardiovascular physician in the Smidt Heart Institute.

Adults were not the only ones who saw an increase in diabetes diagnoses after having COVID-19. A new study published in JAMA Network Open found that there was also a significant rise in cases of type 1 diabetes in children and teenagers after the COVID-19 pandemic.

For the study, researchers analyzed data from 17 studies that included over 38,000 young people who had been diagnosed with diabetes during the pandemic. Compared to 2019, the researchers found that the incidence rate of childhood type 1 diabetes grew by 14% in 2020 and by 27% in 2021.

"It was a much higher incidence than we expected," says senior author Rayzel Shulman, a pediatric endocrinologist at the SickKids Research Institute in Canada. Before the pandemic, the incidence of childhood type 1 diabetes had only been increasing by around 2% to 4% each year.

"Now, all of a sudden, we see a tenfold increase," says Clemens Kamrath, a diabetes researcher at Justus Liebig University in Germany. "This is definitely a significant jump, to an extent and at a speed not thought possible."

The cause of this increase in diabetes diagnoses is still unclear

Currently, researchers say it's not clear what caused the sudden increase in diabetes diagnoses and how long the current trend will continue.

According to Pamela Davis, a professor of medicine at Case Western Reserve University, one possible explanation for the link between COVID-19 and diabetes is that the coronavirus infects beta cells in the pancreas, which make insulin. Other potential explanations include the body's inflammatory response to COVID-19 destroying beta cells or the body sometimes triggering an autoimmune response that attacks its own cells.

In addition, Naveed Janjua, a professor at the School of Population and Public Health at the University of British Columbia, noted that other viral infections, such as hepatitis C, have been associated with developing diabetes.

"It's reasonable to ask, 'Is this an actual increase, or is this just something that accelerated diabetes that was coming anyway in people, but they got it earlier?'" Davis said.

"But even if it's just an acceleration, this is going to be costly," she added. "The human suffering, the risk of complications in the eyes, the blood vessels, the heart, the kidneys, the days of productivity and work lost — all those things will be accelerated. I'm worried about this."

"As we learn how to live with COVID-19, we also have to be prepared to recognize and treat the various conditions linked to its aftereffects," Kwan said. "Our ultimate goal—with every research study we conduct—is to find ways to keep people healthy and able to engage in their everyday activities and lives." (Roberts, BBC, 6/30; Watson, Nature, 7/21; Cedars-Sinai news release, 2/14; Rabin, New York Times, 4/18)