Postprandial Glycemic Control With Automated Insulin Delivery With Control-IQ Technology: The Impact of Meal Composition

Aims: To evaluate the efficiency of the AID system with Control-IQ technology and carbohydrate counting (CHC)-based premeal bolus to control postprandial glucose (PPG) after mixed meals with different macronutrient compositions in adolescents with type 1 diabetes (T1D). Material and methods: In this prospective crossover study, 25 adolescents with T1D using an automated insulin delivery (AID-Tandem Tslim X2 with Control-IQ) consumed three iso-caloric meals (745 kcal) on separate days: a standard meal (56.5% carbohydrate), a high-fat (HF) meal (45.9% fat), and a high-protein (HP) meal (24.4% protein). A CHC-based bolus was administered 15 min before each meal. Continuous glucose monitoring metrics and AID insulin delivery were assessed over 6 h. The primary outcome was 6-h time in range (TIR, 70-180 mg/dL). Results: Six-hour TIR was significantly lower after HF (65.2%) and HP meals (49.9%) compared with the standard meal (84.3%) (p < 0.01 and p < 0.001, respectively). Postprandial glucose exposure (AUC above 140 and 180 mg/dL) was significantly higher after HF and HP meals at both 3 and 6 h. The AID system delivered significantly more insulin than the pre-programmed basal for HF (+26% at 6 h, p < 0.05) and HP meals (+55% at 6 h, p < 0.001), without increasing hypoglycemia. Conclusions: Despite a substantial autonomous increase in insulin delivery, AID systems using Control-IQ technology and a standard CHC-based pre-meal bolus have not achieved adequate postprandial glycemic control after HF and HP meals. Proactively timed, meal-specific insulin strategies are required to improve postprandial outcomes after nutritionally complex meals.