Type 1 diabetes onset in Lombardy region, Italy, during the COVID-19 pandemic: The double-wave occurrence

Background: The Italian Lombardy region has been the epicenter of COVID-19 since February 2020. This study analyses the epidemiology of pediatric type 1 diabetes (T1D) onset during the first two pandemic waves and three previous years. Methods: All the 13 pediatric diabetes centers in Lombardy prospectively evaluated charts of children at T1D onset (0–17 years), during year 2020. After calculating the annual incidence, the data were compared with those of the 3 previous years, using generalized linear models, adjusted for age and sex. Monthly T1D new onsets and diabetic ketoacidosis (DKA) were investigated yearly from 2017 to 2020. Data were extracted from outpatients charts of the pediatric diabetes centers and from the database of the national institute of statistics. Findings: The estimated incidence proportion of T1D was 16/100·000 in 2020, compared to 14, 11 and 12 in 2019, 2018 and 2017, respectively. When adjusting for age and gender, the incidence was significantly lower in 2018 and 2017 compared to 2020 (adjusted incidence ratio: 0.73 and 0.77 respectively, with 95% CI: 0.63 to 0.84, and 0.67 to 0.83; p = 0·002 and p = 0·01), but no difference was found between the years 2020 and 2019. A reduction trend in the percentage of T1D diagnosis during the first wave (March-April) over the total year diagnoses was observed compared to previous years (11·7% in 2020, 17·7% in 2019, 14·1% in 2018 and 14·4% 2017). No difference was observed during the second wave (October-December) (32·8% in 2020, 33·8% in 2019, 34% in 2018, 30·7% in 2017). The proportion of DKA over the total T1D diagnoses during the second wave had higher trend than the first one (41·7% vs 33·3%), while severe DKA over the total DKA appeared higher during the first wave (60% vs 37·1%). Interpretation: The study suggests an increase in the incidence of pediatric T1D in Lombardy throughout the past five years. Pandemic waves may have affected the clinical presentation at onset.