STOCKHOLM – It remains inconclusive whether SARS-CoV-2 infection predisposes children and adolescents to a higher risk of type 1 diabetes. Data from two new studies and a recently published research letter add to the growing body of knowledge on the subject, but still can’t draw any definitive conclusions.
The latest results from a Norwegian and a Scottish study both examine incidence of type 1 diabetes in young people with a history of SARS-CoV-2 infection and were reported at the annual meeting of the European Association for the Study of Diabetes.
A 60% increased risk for type 1 diabetes at least 31 days after SARS-CoV-2 infection (adjusted hazard ratio, 1.63) was found in the Norwegian study, while in contrast, the Scottish study only found an increased risk in the first few months of the pandemic, in 2020, but importantly, no association over a much longer time period (March 2020–November 2021).
In a comment on Twitter on the two studies presented at EASD, session moderator Kamlesh Khunti, MD, professor of primary care diabetes and vascular medicine at the University of Leicester, (England), said: “In summary, two studies showing no or weak association of type 1 diabetes with COVID.”
But new data in the research letter published in JAMA Network Open, based on U.S. figures, also found an almost doubling of type 1 diabetes in children in the first few months after COVID-19 infection relative to infection with other respiratory viruses.
Lead author of the Scottish study, Helen Colhoun, PhD, honorary public health consultant at Public Health Scotland, commented: “Data in children are variable year on year, which emphasizes the need to be cautious over taking a tiny snapshot.”
Nevertheless, this is “a hugely important question and we must not drop the ball. [We must] keep looking at it and maintain scientific equipoise. ... [This] reinforces the need to carry on this analysis into the future to obtain an unequivocal picture,” she emphasized.
Norwegian study: If there is an association, the risk is small
German Tapia, PhD, from the Norwegian Institute of Public Health, Oslo, presented the results of a study of SARS-CoV-2 infection and subsequent risk of type 1 diabetes in 1.2 million children in Norway.
Of these, 424,354 children had been infected with SARS-CoV-2, and there were 990 incident cases of type 1 diabetes.
“What we do know about COVID-19 in children is that the symptoms are mild and only a small proportion are hospitalized with more serious symptoms. But we do not know the long-term effects of COVID-19 infection because this requires a longer follow-up period,” remarked Dr. Tapia, adding that other viral infections are thought to be linked to the development of type 1 diabetes, in particular, respiratory infections.
The data were sourced from the Norwegian Emergency Preparedness Register for COVID-19, which gathers daily data updates including infections (positive and negative results for free-of-charge testing), diagnoses (primary and secondary care), vaccinations (also free of charge), prescribed medications, and basic demographics.
“We link these data using the personal identification number that every Norwegian citizen has,” explained Dr. Tapia.
He presented results from two cohorts: firstly, results in children only, including those tested for SARS-CoV-2 infection, and secondly, a full national Norwegian population cohort.
Regarding the first cohort, those under 18 years who tested positive for SARS-CoV-2 infection, from March 2020 to March 2022, had a significantly increased risk of type 1 diabetes at least 31 days after infection, with an adjusted hazard ratio of 1.63 (95% confidence interval, 1.08-2.47; P = .02). Adjustments were made for age, sex, non-Nordic country of origin, geographic area, and socioeconomic factors.
For children who developed type 1 diabetes within 30 days of a SARS-CoV-2 infection, the HR was 1.26 (95% CI, 0.72-2.19; P = .42), which did not reach statistical significance.
“The fact that fewer people developed type 1 diabetes within 30 days is not surprising because we know that type 1 diabetes develops over a long period of time,” Dr. Tapia said.
“For this reason, we would not expect to find new cases of those people who develop type 1 diabetes within 30 days of COVID-19 infection,” he explained. In these cases, “it is most likely that they already had [type 1 diabetes], and the infection probably triggered clinical symptoms, so their type 1 diabetes was discovered.”
Turning to the full population cohort and diagnoses of type 1 diabetes over 30 days after SARS-CoV-2 infection, the Norwegian researchers found an association, with an HR of 1.57 (95% CI, 1.06-2.33; P = .03), while diagnosis of type 1 diabetes at 30 days or less generated a hazard ratio of 1.22 (95% CI, 0.72-2.19; P = .42).
“So very similar results were found, and after adjustment for confounders, results were still similar,” reported Dr. Tapia.
He also conducted a similar analysis with vaccination as an exposure but found no association between vaccination against SARS-CoV-2 and diagnosis of type 1 diabetes.
“From these results, we conclude that this suggests an increase in diagnosis of type 1 diabetes after SARS-CoV-2 infection, but it must be noted that the absolute risk of developing type 1 diabetes after infection in children is low, with most children not developing the disease,” he emphasized. “There are nearly half a million children who have been infected with SARS-CoV-2 in Norway, but only a very small proportion develop type 1 diabetes.”