Endocrine Abstracts

JOINT1913

Introduction: Type 1 diabetes (T1D) incidence is rising globally, with significant regional variation, ranging from low rates in Asia (2. 4-3. 2 per 100, 000 person-years) to the highest in Scandinavia and Sicilia (up to 65 per 100, 000 person-years). Despite extensive research, the contributing factors — climate, genetic, environmental, or lifestyle-related, remain unclear. Therefore, data from highly homogeneous populations, such as Lithuanian, may contribute to a better understanding of these factors. This study examines 21-year trends in childhood T1D incidence and seasonal patters in Lithuania.

Methods: The current study relied on the incidence data sourced from the T1D Database of Lithuanian children, while population data were procured from the Lithuanian Department of Statistics. The annual incidence rates for more than two decades were computed utilizing established methodologies (per 100, 000 person-years in children aged 0-14 years (from this point onward per 100, 000 person-years). The study included 2, 472 (1221 boys) patients with T1D diagnosis before the age of 15, permanent residents of Lithuania.

Results: During 2001-2022, the mean standardized incidence rate (IR) was 24. 09 per 100, 000 person-years (95% CI 20. 89, 27. 28). The IR scaled from 11. 4 to 40. 8 per 100, 000 person-years, with the lowest in 2001-2002, reaching its peaks in 2017 (36. 3 per 100, 00 person-years), 2021 (40, 8 per 100, 000 person-years) and 2022 (34 per 100, 000 person-years). Analysis of the trends in age subgroups, showed the most rapid increase in young teenagers (10-14 years), with more steadily increasing incidence in younger groups (0-4 years and 5-9 years). No significant disparity in incidence trends was noticed between male and female cohorts. The boys-to-girls ratio varied from 0. 7 to 1. 53 during the study period, however, the overall ratio was 1. 00. The majority of new T1D cases (54, 5%) were diagnosed from October to March, and the lowest incidence rate was during late spring and summer months (May-July).

Conclusion: This study demonstrates arapidly increasing incidence of T1D in Lithuanian children over a 21-year period, with the incidence peaking at 40. 8 cases per 100, 000 person-years in 2021, rating Lithuania among the top three European countries. The seasonal distribution of new cases, with the majority occurring during the darker months of the year, suggests a potential role of reduced sunlight exposure and lower vitamin D levels, as well as increased school related stress and viral infections during autumn and wintermonths. However, additional contributing factors are likely involved, underscoring the need for further research to elucidate the underlying mechanisms driving this trend.