Comparing Automated Lyumjev® Delivery with Carbohydrate Counting, Qualitative Meal-Size Estimation, and Fully Closed-Loop in Type 1 Diabetes: A Pilot, Randomized, Crossover Trial

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Objective: Determining prandial insulin needs by carbohydrate counting is a challenging task for many people with type 1 diabetes (PwD). We developed a novel automated insulin delivery (AID) system using ultrarapid lispro insulin (Lyumjev ® ), replacing carbohydrate counting with qualitative meal-size estimation and meal detection. Research Design and Methods: We performed a randomized crossover pilot trial comparing 3 weeks of AID with carbohydrate counting (AID-count) with (i) AID with qualitative meal-size estimation (i.e., defining a meal as low, medium, high, or very high in carbohydrate content; AID-estimate) and (ii) AID with meal detection (i.e., fully closed-loop; AID-fully) in adults with type 1 diabetes (T1D). The trial was registered (NCT06021158). Results: Twelve participants completed the study (eight females; mean [SD]: age 38 [16] years, HbA1c 7.0% [0.7], total daily insulin dose 0.64 [0.22] U/[kg·d]). There were no differences greater than 5% in the overall time in range between AID-estimate and AID-fully compared with AID-count, and thus the differences were not considered clinically significant based on the international consensus on time in range (AID-count vs. AID-estimate: 75.4% [16.3] vs. 72.9% [13.2], P = 0.191; AID-count vs. AID-fully: 75.4% [16.3] vs. 71.0% [10.6], P = 0.192). The differences in time spent in hyperglycemia were not statistically significant, and the times spent in hypoglycemia were low and not different between interventions. There were no episodes of severe hypoglycemia or diabetic ketoacidosis in any intervention. Conclusions: In this pilot study, the AID system using Lyumjev simplified or alleviated carbohydrate counting without degrading glucose control more than 5%. Larger studies are warranted.