Has the COVID-19 pandemic affected the incidence of type 1 diabetes in Italy? Analysis on population-based registries over a 33-year period

ABSTRACT

Introduction: It is currently not well known if the incidence of type 1 diabetes (T1D) changed during COVID-19 pandemic. Objective(s) Basing on two population-based registries collecting data of new cases in Italy since 1989, we analyzed changes on incidence in a long and short period. Method(s) All new cases of T1D in children aged between 0.5 and 14, recruited by the Piedmont and Marche registries during 1989- 2021, were considered. Poisson regression was used to estimate the incidence trend, adjusted for age and sex, for the period 1989-2019 and to predict the incidence in the years 2020 and 2021. The observed rates in the years of the pandemic were compared with those predicted by the model and with those of the three-year prepandemic period 2017-2019. Result(s) Between 1989 and 2021, 4009 children diagnosed with T1D were observed, 2144 males (53.5%). The standardized incidence for the entire period was 16.9 (95%CI 14.4-17.5) per 100,000 personyears, 17.6 and 16.2 for males and females respectively. The incidence over time increased from 12.0 (95% CI 9.6-14.4) in 1989 to 20.9 (95% CI 17.5-24.9) in 2019, with an annual increasing trend of 1.9% (95% CI 1.5-2.2). The observed incidence rates in 2020 and 2021 were 21.6 (95% CI 18.3-25.3) and 26.7 (95% CI 23.0-30.9) respectively, not significantly different from the ones predicted by the model, 21.6 (95%CI 20.3-23.0;p = 0.995) and 22.0 (95%CI 20.5- 26.6;p = 0.074). The mean incidence rate of T1D in the pre-pandemic 3 years, equal to 20.5 (95%CI 18.6-22.5), was not different from that of 2020, but significantly lower than that observed in 2021 (<0.001). Conclusion(s) The incidence of T1D < 15 years continues to increase over time. During 2020-2021, the observed incidence was in line with the expected trend 1989-2019. However, narrowing the analysis to 2017-2021, there was a higher incidence in 2021. Continuous observation of T1D in children is critical to better understanding the role of COVID-19 in influencing the disease.