National study calls into question COVID-diabetes link in young people

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New research, being presented at this year’s European Association for the Study of Diabetes (EASD) Annual Meeting in Stockholm, Sweden (19–23 Sept), found that testing positive for SARS-CoV-2—the virus that causes COVID-19—is associated with an increased incidence of new-onset type 1 diabetes in people aged younger than 35 years, but this is restricted to the first month after infection, and is more likely explained by increased testing around the time of diabetes diagnosis and COVID-19 precipitating diabetes in those already developing it.

The study compared data from COVID-19 testing results with the Scottish diabetes register for the period March 2020 to November 2021. It tested whether an increase in diabetes risk was associated with this period of COVID-19 infection.

“Our findings raise questions about whether there is a direct link between COVID-19 infection and new-onset type-1 in children and adults,” says Helen Colhoun, coauthor from Public Health Scotland. She also works at the University of Edinburgh. “A recent report by the U.S. Centers for Disease Control and Prevention, which examined two large insurance-claim databases of children under 18, found that children with COVID-19 had 2.5 times the chance of being diagnosed with diabetes in the first month after infection than their counterparts who were never infected. If replicated, this is going to create a large number of people with newly diagnosed diabetes and might also alter the risk–benefit balance for COVID-19 vaccination in young children. We did not confirm this finding.

Type 1 diabetes usually develops during childhood or adolescence. However, the immune system attacks insulin producing cells. It is not clear why. One theory suggests that the immune system could be triggered by a virus infection, which then accidentally attacks insulin-producing cell. People with normal blood sugar levels have been shown to be at higher risk of developing type 1 diabetes due to viral infections.

Colhoun and his colleagues compared individual-level data from the Electronic Communication of Surveillance Database on confirmed PCR-confirmed SARS/CoV-2 infections. This database captures all PCR tests for COVID-19 nationwide, along with the precise dates of all type 1 diabetes diagnoses from the Scottish national register (which is updated daily).

All positive lateral flow tests were required to be confirmed by PCR during the study period.

This study was important because the dates of diabetes diagnosis were exact, unlike other studies. This allowed for the establishment of the time sequence of type 1 and COVID-19.

Between March 2020 to November 2021, a total 359,080 children or adults had at least one SARS-CoV-2 diagnosis, and 1,074 were diagnosed as having type 1 diabetes.

Contrary to many previously reported studies, there was no association between SARS/CoV-2 infection with new-onset type-1 diabetics 30 days or longer after infection.

The researchers found that adults and children who had a positive SARS-CoV-2 testing were 2.5 times more likely to develop diabetes within 30 days than those without a previous diagnosed infection. This risk was even greater for those under 16 years.

However, the authors make strong arguments against a causal effect from COVID-19 that could be underlying this association.

Further analysis of COVID-19 testing patterns in relation to type 1 diabetic diagnosis revealed an increased frequency for SARS-CoV-2 tests in the days preceding and following diabetes presentation. These were positive and negative results. The authors believe that this association could partly be explained in part by higher infection detection at this time.

The average time between the onset of type-1 diabetes symptoms and diagnosis for those under 16 years old in England is approximately 25 days, according to the authors. It is possible that many of those who tested positive to COVID-19 within 30 day of being diagnosed with diabetes already had type 1 diabetes.

The analysis also showed no association between COVID-19 vaccine status and new-onset type-1 diabetes in adults (only a few children were vaccinated during this period), further supporting the hypothesis of a causal effect from SARS-CoV-2 infections on the development of diabetes.

The researchers also looked at trends in type 1 diabetes incidence in Scottish children aged 0–14 years before and during the pandemic, finding that the incidence in 2020–2021 was around 20% higher than the 7-year average for 2015–2021.

However, they point out that based on estimates from England, the time course of the increase in diabetes incidence in those aged 0–14 years predated most of the cumulative incidence of SARS-CoV-2 infection in this age group (June 2021 onwards), suggesting a lack of causal association between COVID-19 and rates of diabetes.

“Our findings show that other causes are needed in relation to the increase incidence of type-1 diabetes,” says Professor Paul McKeigue from Public Health Scotland, and the University of Edinburgh. “We must consider what happened during the pandemic and whether other environmental factors such as sunlight and vitamin D levels might have been altered during lockdown.

The authors note that their study was not comprehensive, and further analysis is required to capture the most recent part of the pandemic as well as its variants. They also noted that most COVID-19 cases in younger adults were not detected until mass testing was done in the third-quarter of 2020. This could have limited the conclusions that could be drawn.

COVID-19 infection may increase type 1 diabetes risk, suggests a nationwide study of over 1.2 million children

More information:
Paul M. McKeigue et.al, Relationship of Incident Type 1 diabetes to Recent COVID-19 infection: Cohort Study Using eHealth Record linkage in Scotland Diabetes Care (2022). DOI: 10.2337/dc22-0385

National study calls into question COVID-diabetes link in young people (2022, September 23)
Retrieved 23 September 2022
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