ESPE Abstracts

Background: The annual incidence rate (IR) of childhood-onset type 1 diabetes mellitus (T1D) among Estonian children under the age of 15 between 1983 and 2006 was 12.6 per 100 000 per year, with the highest incidence rate in the age-group 10-14.9 years. During this time period the most rapid increase in incidence was seen in age-group 0-4.9 years, with a 9.3% increase annually.

Objective: To calculate the incidence of T1D among Estonian children in 2007–2022 and compare these findings with the data from 1983 to 2006. To analyse the impact of the COVID-19 pandemic on incidence of childhood onset diabetes in Estonia.

Subjects and Methods: Data from 1999 to 2022 were collected through population-based registries from the two centres where all children diagnosed with T1D in Estonia initially receive care. Statistics from earlier time periods were obtained from previously published data. The subjects were divided into three age-groups: 0–4.9 years, 5.0–9.9 years and 10.0–14.9 years. Eight-year time periods were compared: 1983-1990, 1991-1998, 1999-2006, 2007-2014 and 2015-2022.

Results: Between 2007 and 2022, 1104 new cases of T1D were diagnosed in children aged 0-14.9 years in Estonia. The age-standardised incidence rate for that time period was 33.4 per 100 000 persons at risk per year [95% confidence interval (CI) 30.1-35.0]. The overall highest incidence, 43.9 (95% CI 38.4-49.3), was seen in the oldest age-group during 2015-2022. The relative increase in the crude incidence between 2007-2022 was 12.7%, i.e 1.6% annually. During the last two time periods, the most rapid yearly increase in T1D incidence was seen in 5.0-9.9 year olds, at a rate of 2.9% annually (RR 1.23, 95% CI 1.01-1.50). The highest incidence of childhood-onset T1D in Estonian children ever seen was in 2021, during the COVID-19 pandemic peak, with an IR of 45.8 per 100 000 (95% CI: 26.9-54.8). There was a statistically significant increase in incidence during 2021 when compared to the last two time periods (2007-2022) which had an average IR of 32.9 per 100 000 (95% CI: 20.9-34.8) [rate ratio (RR) 1.39; 95% CI: 1.14-1.71; p-value <0.01].

Conclusions: The incidence of childhood-onset type 1 diabetes mellitus continues to rise in Estonia. A significant increase in the incidence rate of T1D was seen in Estonian children during the COVID-19 pandemic peak in 2021.