Trends and cyclic variation in the incidence of childhood type 1 diabetes in two Italian regions over 33 years and during the COVID‐19 pandemic.

Aim: There is conflicting evidence about the impact of the COVID‐19 pandemic on the incidence of type 1 diabetes. Here, we analysed long‐term trends in the incidence of type 1 diabetes in Italian children and adolescents from 1989 to 2019 and compared the incidence observed during the COVID‐19 pandemic with that estimated from long‐term data. Materials and Methods: This was a population‐based incidence study using longitudinal data from two diabetes registries in mainland Italy. Trends in the incidence of type 1 diabetes from 1 January 1989 to 31 December 2019 were estimated using Poisson and segmented regression models. Results: There was a significant increasing trend in the incidence of type 1 diabetes of 3.6% per year [95% confidence interval (CI): 2.4‐4.8] between 1989 and 2003, a breakpoint in 2003, and then a constant incidence until 2019 (0.5%, 95% CI: ‐1.3 to 2.4). There was a significant 4‐year cycle in incidence over the entire study period. The rate observed in 2021 (26.7, 95% CI: 23.0‐30.9) was significantly higher than expected (19.5, 95% CI: 17.6‐21.4; p =.010). Conclusion: Long‐term incidence analysis showed an unexpected increase in new cases of type 1 diabetes in 2021. The incidence of type 1 diabetes now needs continuous monitoring using population registries to understand better the impact of COVID‐19 on new‐onset type 1 diabetes in children. [ABSTRACT FROM AUTHOR]