A Randomized Crossover Trial to Compare Automated Insulin Delivery (the Artificial Pancreas) with Carbohydrate Counting or Simplified Qualitative Meal-Size Estimation in Type 1 Diabetes

Objective: Qualitative meal-size estimation has been proposed instead of quantitative carbohydrate (CHO) counting with automated insulin delivery. We aimed to assess the non-inferiority of qualitative meal-size estimation strategy. 

Research Design and Methods: We did a two-center randomized crossover non-inferiority trial to compare 3 weeks of automated insulin delivery with (i) carbohydrate counting and (ii) qualitative meal-size estimation in adults with type 1 diabetes. Qualitative meal-size estimation categories were low, medium, high, or very high CHO and were defined as <30 g, 30-60 g, 60-90 g, and >90 g of CHO, respectively. Prandial insulin boluses were calculated as the individualized insulin-to-CHO ratios x 15, 35, 65, and 95, respectively. Closed-loop algorithms were otherwise identical in the two arms. The primary outcome was time in range 3.9–10.0 mmol/L, with a pre-defined non-inferiority margin of 4%. 

Results: 30 participants completed the study (20 females, age 44 (SD 17) years, A1c 7.4% (0.7%)). The time in 3.9-10.0 mmol/L was 74.1% (10.0%) with carbohydrate counting and 70.5% (11.2%) with qualitative meal-size estimation; mean difference -3.6% (8.3%; non-inferiority p=0.78). Times <3.9 mmol/L and <3.0 mmol/L were low (< 1.6% and < 0.2%) in both two arms. Automated basal insulin delivery was higher in the qualitative meal-size estimation arm (34.6 vs. 32.6 U/day, p=0.003).

Conclusions: Though the qualitative meal-size estimation method achieved a high time in range and low time in hypoglycemia, non-inferiority was not confirmed. 

(Funded by NIH. ClinicalTrials.gov. NCT04031599).