Epidemiological Trends and Seasonal Patterns in Childhood Type 1 Diabetes: Insights From 2001 to 2024 in Lithuania

Type 1 diabetes (T1D) incidence is rising globally, with significant regional variation. Data from highly homogeneous populations, such as Lithuanian, may contribute to a better understanding of contributing T1D factors. This study examines 24-year trends in childhood T1D incidence and seasonal patterns in Lithuania.

The annual incidence rates (IRs) were computed utilizing established methodologies per 100,000 children <15 years. The study included 2369 (1181 boys) patients with T1D.

During 2001-2024, the mean IR was 21.4 per 100,000 < 15 years (95% CI: 20.89, 27.28). The incidence rose from 10.8 to 36.4 per 100,000 children under 15 years of age, with notable peaks observed in 2021 and 2022, temporally aligning with the highest COVID-19 infection waves. Subgroup analysis showed the most rapid increase in young teenagers (10-14 years). Most new cases (63.5%) were diagnosed from September to March.

This study demonstrates a rapidly increasing incidence of T1D in Lithuanian children over a 24-year period and is one of the highest in European countries. The seasonal distribution of new cases has been speculated to be due to reduced sunlight exposure and lower vitamin D levels, as well as increased school related stress and viral infections during autumn and winter months. However, additional contributing factors are likely involved, underscoring the need for further research.