Supplementary Material for: Regional deprivation and diabetic ketoacidosis at type 1 diabetes diagnosis in children and adolescents: International comparison among 6 countries

Introduction: The incidence of diabetic ketoacidosis (DKA) at the time of diagnosis of type 1 diabetes in youth varies between countries and is influenced by socioeconomic factors. We investigated the relationship between regional deprivation indices and DKA at diagnosis of type 1 diabetes in six countries. Methods: We analyzed children 0.5 to 17.0 years old diagnosed with type 1 diabetes between 2019-2022 across six diabetes registries. Regional deprivation index within each country was standardized to compare each individual’s socioeconomic status internationally. Log-binomial regression models assessed the association between the standardized deprivation index and DKA, with sex, age group, and year as covariates. Results: Among 21,020 children (mean age 9.08 [SD 4.19] years) the DKA rate of 36.5%. Cohorts were: Germany (n=13,561, DKA 32.5%), Italy (4,659, 42.5%), Colorado USA (1,318, 54.9%), Wales (769, 35.2%), New Zealand (407, 43.7%), and Slovenia (306, 37.6%). Deprivation was associated with increased risk of DKA in children 0.5-< 6 (OR 1.16 [95% CI 1.10 - 1.23], p < 0.0001) and 6-<12 years of age (1.05 [1.05 – 1.11], p = 0.02). Female sex increased risk of DKA (1.06, [1.00 - 1.13], p = 0.04). The proportion of DKA was lower in 2019 than in 2020, 2021, and 2022 (each p < 0.0001). Conclusion: Deprivation was significantly associated with the risk of DKA at the diagnosis of type 1 diabetes, and DKA was more common during the pandemic years 2020-2022 than in 2019. Younger children appear to be more vulnerable to deprivation than older patients. Understanding and reducing local and demographic-specific disparities is essential for effective intervention.