During the COVID-19 pandemic, an increase in the chronic autoimmune disease type 1 diabetes was observed in children. Researchers at Helmholtz Munich and TU Dresden, in cooperation with the Kassenärztliche Vereinigung Bayern (KVB), have now investigated whether there is a temporal association between infection with the SARS-CoV-2 virus and the development of type 1 diabetes. The team of researchers explored data of over 1.1 million statutorily insured children born between 2010 and 2018 in Bavaria.

Different studies have documented an increased incidence of type 1 diabetes during the COVID-19 pandemic. However, none of the studies distinguishes between children with and without SARS-CoV-2 infection. Researchers were now able to gain new insights: the KVB data set provides information on whether children diagnosed with type 1 diabetes previously had COVID-19. This allows an analysis of the temporal relationship between a COVID-19 diagnosis and the diagnosis of type 1 diabetes.

Among the analyzed children without type 1 diabetes diagnosis before the start of the pandemic, 16.6 percent had a diagnosis of COVID-19 between January 2020 and December 2021.

SARS-CoV-2 infection was associated with an increased risk of type 1 diabetes in children

The researchers' initial findings were consistent with data from Germany and other countries: the incidence rate of type 1 diabetes in children between the ages of 2 and 12 years was around 50 percent higher in the years 2020 to 2021 as compared to the incidence rate in 2018 to 2019. Important and novel, they found that the development of type 1 diabetes in 2020 to 2021 was higher in the children with COVID-19.

The likelihood to develop type 1 diabetes was increased by 57 percent in children who had a confirmed SARS-CoV-2 infection compared to non-infected children. The increase in type 1 diabetes incidence occurred in the same quarter as the COVID-19 diagnosis and also in later quarters.

The new data point to a direct effect of SARS-CoV-2 infection on the development of type 1 diabetes.

"We are cautious in our interpretation, but the findings suggest that the virus could either promote initiation of the underlying autoimmunity in type 1 diabetes or accelerate the progression of the disease in children with existing autoimmunity," says Ezio Bonifacio, last author of the study. Further studies will be needed to elucidate the exact mechanism driving the increased incidence of type 1 diabetes during the COVID-19 pandemic in young children.

The findings are published in the journal JAMA.