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Children between 4 months and 2 years old who have had covid-19 are more likely to have antibodies that attack cells that make insulin (胰岛素), a feature of type 1 diabetes.

Insulin, a hormone that regulates the body’s blood sugar levels, is made in the pancreas (胰腺) by cell clusters known as islets of Langerhans. In some cases, the body can develop an autoimmune response to these islets and produce auto-antibodies against them. Too many of these over time will kill enough islets to trigger type 1 diabetes, where the body can’t produce its own insulin.

“The presence of these auto-antibodies more or less means that there’s a 100 per cent path to [type 1 diabetes]” says Anette-Gabriele Ziegler at the Technical University of Munich in Germany.

One of the risk factors for type 1 diabetes is thought to be some viral infections, including SARS-CoV-2, the virus that causes covid-19. A rise in diabetes cases linked to covid-19 has been reported, but the mechanism behind it isn’t known.

To investigate, Ziegler and her colleagues monitored 885 children between the ages of 4 months and 2 years old, who were all identified as having at least a small risk of developing islet auto-antibodies. Of the children, 170 had SARS-CoV-2 antibodies, suggesting they had previously had covid-19.

The children who had these antibodies were twice as likely to develop islet auto-antibodies as those who hadn’t been infected. Those who caught covid-19 before they were 18 months old had a 5 to 10 times higher risk of developing the auto-antibodies, making them the most at risk group.

“We would love to see if vaccinating children from 6 months can prevent the autoimmunity that leads to type 1 diabetes,” says Ziegler.