Age-Dependent Bolus Settings: Insulin-to-Carbohydrate Ratios and Insulin Sensitivity Factors in Pediatric Patients with Type 1 Diabetes on Conventional CSII in the DPV Registry

<b><i>Introduction:</i></b> Effective bolus settings for insulin-to-carbohydrate ratios (ICRs) and insulin sensitivity factors (ISFs) are crucial for glycemic control in pediatric patients with type 1 diabetes on insulin pumps. Standard calculation methods based on the total daily insulin dose (TDD) often fall short for children. This study examined insulin pump settings for ICR and ISF in pediatric patients, considering diurnal variation, age, sex, and body mass index (BMI). The goal was to provide data-driven recommendations for initial bolus settings. <b><i>Methods:</i></b> We analyzed insulin pump settings in 7697 pediatric patients with type 1 diabetes in the DPV registry (Diabetes Prospective Follow-up) from Germany, Austria, Switzerland, and Luxembourg. Patients aged 1 to <18 years, postremission (diabetes duration >1 year, insulin dose ≥0.5 IU/kg/d), with good metabolic control (HbA1c ≤7.5%), using insulin pumps with short-acting analog insulin in 2023, were included. Automated insulin delivery system users were excluded. Patients were grouped by age (<6, 6 to <12, 12 to <18 years), BMI percentiles (<P25, P25-75, >P75), and sex. <b><i>Results:</i></b> Older children required more insulin, with lower ICRs and ISFs. Insulin requirements peaked in the morning with the lowest ICR and ISF, with medians (interquartile ranges): <6 years: 11.2 g carbs/IU (9.1-14.0) and 1:150 mg/dL (70-228); 6 to <12 years: 8.7 g carbs/IU (7.0-10.7) and 1:90 (50-140); and 12 to <18 years: 6.1 g carbs/IU (5.0-7.7) and 1:50 (40-80). ISF was highest in the late evening in all age groups, while a higher BMI-SDS was associated with a lower ISF. Girls above 6 years had lower ICR but similar ISF to that of boys. The factor obtained by multiplying ISF and TDD was comparable in all age groups and BMI categories. <b><i>Conclusion:</i></b> Our real-world findings on CSII settings in a large cohort of children with sufficient metabolic control highlight the inadequacy of a single TDD-based calculation formula, as insulin requirements varied by age, time of day, sex, and BMI. These findings may serve as a reference for commonly used age-dependent parameters for clinicians in establishing initial CSII settings before individualized dose titration and optimization.