Background 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. Methods 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. Results 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. Conclusions 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.
Stankutė et al. (2026) studied this question.