Comparison of Diluted Insulin (U10) Versus Standard (U100) Insulin in Automated Insulin Delivery Systems: Reducing Time Below Range in Young Children.
BACKGROUND Treating young children with Type 1 diabetes (CwT1D) is challenging due to their very small need for insulin. We investigated the safety of diluted insulin (U10) in the AID system and how its use affected glycaemic outcomes compared to standard insulin. METHODS Patients aged 0-4 years who initiated treatment with diluted insulin in an AID system during the years 2020-2025 were identified from the diabetes registry (N = 19). They had a maximum daily insulin dose of ≤ 6 units. An age and gender-matched control group (N = 27) using standard insulin (U100) in an AID system was determined. Longitudinal CGM outcomes were analysed within the treatment group from the start of diluted insulin and between groups from diagnosis over 12 months to assess time-by-treatment effects. RESULTS After 3 months of diluted insulin use, TBR < 3.9 and TBR < 3.0 decreased significantly (from 4.6% ± 4.1% to 2.7% ± 2.5%, p = 0.008; from 1.2% ± 1.8% to 0.4% ± 0.6%, p = 0.01, respectively) and remained low through 12 months. Compared with controls, children using diluted insulin had lower TBR < 3.9 mmol/L at later follow-up visits. In the HbA1c-adjusted mixed-effects model, the between-group difference in change from 3 months was -1.85 percentage points at 9 months (95% CI: -3.26 to -0.44, p = 0.010) and -1.52 percentage points at 12 months (95% CI: -2.92 to -0.13, p = 0.032). No significant between-group changes in other CGM measures over time were observed. CONCLUSION The use of diluted insulin in young CwT1D, who require low insulin doses and use an automated insulin delivery system, reduces time below range with no evidence of increased hyperglycaemia.