A significant increase in cases of type 1 diabetes in children has been reported by a large children's hospital in California during the COVID-19 pandemic. As to whether COVID-19 is directly causing this increase, the jury is still out, with the study’s authors urging that their findings be interpreted with caution.

The study, published in the journal JAMA Pediatrics, found there was a 57 percent increase in new-onset type 1 diabetes admissions in children in the first year of the pandemic. Between March 19, 2020, and March 18, 2021, 187 children were admitted to Rady Children’s Hospital, San Diego, compared to 119 the previous year.  

Cases of type 1 diabetes have been rising, even before the pandemic. The new study included five years of prior data, finding the increase observed in the first year of the pandemic was significantly higher than the expected annual rise.

The study also noted a 19 percent reduction in inpatient admissions between 2019 and 2020, and no substantial changes in the number of children using the pediatric endocrine clinic or living in the local area.

The increase in cases is, therefore “unlikely to reflect changes in referral number or pattern,” the study authors write.

Pediatric cases of type 1 diabetes were also more likely to be diagnosed with diabetic ketoacidosis – a complication of diabetes that makes the blood more acidic and can be fatal if untreated. Treatment usually involves an intravenous insulin infusion, the frequency of which increased from around 41 percent in the five years leading up to the pandemic to almost 50 percent in the pandemic’s first year, the study found.

However, a causative link between COVID-19 and type 1 diabetes in children has not been established. Only 2.1 percent of the children involved in the study tested positive for COVID-19 at the time of their admission, and there were no antibody tests done to find out if they had ever been infected.

“We do not know what factors from the pandemic, either directly or indirectly, account for this increase,” study author Jane Kim, clinical professor of pediatrics at UC San Diego Health, told Gizmodo.

“There is not yet enough evidence from us or other groups to conclude that COVID is causative for diabetes in children.”

Studies from these other groups support the findings of this latest study, but are equally limited.

A CDC report from earlier this month, for example, found that under 18s were more likely to be diagnosed with diabetes if they had been infected with COVID-19 over 30 days ago, compared to those who hadn’t been infected. A diabetes diagnosis was also more likely in recent COVID-19 patients than in people who had another respiratory infection prior to the pandemic.

Importantly, the study didn’t differentiate between type 1 and type 2 diabetes, and has come under some criticism for failing to account for other factors that could contribute to a diabetes diagnosis, including obesity, underlying health conditions, and race.

Another study, based in Germany, reported an increase in type 1 diabetes cases “with a delay in the peak incidence of type 1 diabetes by [approximately] three months after the peak COVID-19 incidence and also after pandemic containment measures.”

However, they suggest this is more likely an indirect effect of the pandemic itself than COVID-19. Increased social isolation, and poorer mental health, for example, could contribute to the increase in type 1 diabetes cases.

Nonetheless, the evidence points to a potential link between COVID-19, type 1 diabetes in children, and pandemic containment efforts, which warrants further research.