Supplementary Material for: Increasing Contribution of Adolescent Type 1 Diabetes Drives Incidence Rates in Poland - a 40-year-long Observational Study

Introduction: The incidence of childhood type 1 diabetes (T1D) has increased globally in recent decades. Analyzing incidence trends can elucidate patterns and predict future healthcare burdens. We aim to assess changes in the incidence and prevalence of pediatric type 1 diabetes over 40 years in Central Poland.

Methods: This prospective observational study in Lodz Province registered all new-onset type 1 diabetes cases in children 0-14 years old admitted from 1983 to 2022 to reference centres for pediatric diabetes. Diagnoses were based on established guidelines, and other types of diabetes were excluded. Population data were obtained from Poland's General Statistical Office.

Results: The incidence rate of type 1 diabetes increased tenfold, from 3.29/100,000 (95%CI: 1.85-4.73) in 1983 to 32.43 (26.42-38.44) in 2022, with an annual percentage change of 5.73% (4.99%-6.44%) and two distinct increase periods: rapid in 1983-2005 (7.38% [6.30-10.52%]) and slower in 2005-2022 (3.65% [-0.86-5.13%]). Incidence rates in 0-4-year-olds were significantly lower than in 5-9 and 10-14-year-olds. (p<0.0001). While incidence plateaued in the 0-4-year-olds after 2007, it consistently increased in older children. Most new cases were diagnosed in winter (December-February, a mean difference from the remaining seasons of 29±11.6% points, p<0.0001). The prevalence of type 1 diabetes increased, reaching 177.21/100,000 (163.18-191.24) in 2022.

Conclusions: Over the past 40 years, the incidence of pediatric type 1 diabetes in Central Poland has increased significantly, though the rate is slowing. Most new cases occur in children 10 years old and older, so healthcare systems should adapt to young adults who are extensive users of new diabetes technologies.

引言：近数十年来，全球儿童1型糖尿病（type 1 diabetes, T1D）的发病率呈上升趋势。分析发病率变化趋势可阐明疾病流行模式并预测未来医疗负担。本研究旨在评估波兰中部地区40年间儿童1型糖尿病的发病率与患病率变化情况。

方法：本研究为罗兹省开展的前瞻性观察研究，纳入了1983年至2022年间就诊于儿童糖尿病专科转诊中心的全部0~14岁儿童新发1型糖尿病病例。诊断标准遵循既定临床指南，并排除其他类型糖尿病患者。人口统计数据来源于波兰统计局（General Statistical Office）。

结果：1型糖尿病发病率增长至最初的10倍，从1983年的3.29/10万（95%置信区间：1.85~4.73）升至2022年的32.43/10万（26.42~38.44），年度百分比变化率为5.73%（4.99%~6.44%），且存在两个显著的增长阶段：1983~2005年为快速增长期（7.38%，95%置信区间：6.30%~10.52%），2005~2022年为缓慢增长期（3.65%，95%置信区间：-0.86%~5.13%）。0~4岁组的发病率显著低于5~9岁及10~14岁组（p<0.0001）。2007年后，0~4岁组发病率趋于平稳，而年长儿童组的发病率则持续上升。多数新发病例确诊于冬季（12月至次年2月，与其他季节相比平均高出29±11.6个百分点，p<0.0001）。1型糖尿病患病率亦呈上升趋势，2022年达到177.21/10万（163.18~191.24）。

结论：近40年来，波兰中部地区儿童1型糖尿病的发病率显著上升，不过增长速率已有所放缓。多数新发病例集中于10岁及以上儿童群体，因此医疗系统应适配大量使用新型糖尿病诊疗技术的年轻患者群体。