We did a randomized crossover non-inferiority trial to compare 3 weeks of automated insulin delivery with (i) carbohydrate counting and (ii) qualitative meal-size estimation (low, medium, high, or very high carbohydrate (CHO)) in 30 adults with T1D (20/30 females, age 44±17 yrs, A1c 7.4±0.7%) . Low, medium, high, and very high CHO meals were defined as <30 g CHO, 30-60 g CHO, 60-90 g CHO, and >90 g CHO, respectively, and their 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 time in range 3.9-10.0 mmol/L (primary outcome) was 74% (SD 10%) with carbohydrate counting and 71% (11%) with qualitative meal-size estimation; difference -3.6% (95% CI, -0.6% to -6.5%) which crossed the pre-specified non-inferiority margin of 4%. Times <3.9 mmol/L and <3.0 mmol/L were low 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) . We conclude that non-inferiority of the qualitative meal-size estimation was not confirmed, though this method achieved a high time in range and low time in hypoglycemia. The qualitative meal-size estimation method may benefit from larger prandial boluses and more responsive post-meal automatic basal delivery.


A.Haidar: Consultant; Eli Lilly and Company, Research Support; ADOCIA, Dexcom, Inc., Eli Lilly and Company, Tandem Diabetes Care, Inc. L.Legault: Advisory Panel; Abbott Diabetes, Insulet Corporation, Novo Nordisk A/S, Other Relationship; Eli Lilly and Company, Research Support; AstraZeneca, Merck & Co., Inc. M.Raffray: None. N.Gouchie-provencher: None. A.Jafar: None. M.Devaux: None. M.Ghanbari: None. R.Rabasa-lhoret: Consultant; HLS Therapeutics Inc., Pfizer Inc., Other Relationship; Abbott Diabetes, AstraZeneca, Boehringer Ingelheim International GmbH, Dexcom, Inc., Eli Lilly and Company, Insulet Corporation, Janssen Pharmaceuticals, Inc., Medtronic, Merck & Co., Inc., Novo Nordisk Canada Inc., Sanofi, Vertex Pharmaceuticals Incorporated, Research Support; Canadian Institutes of Health Research, Cystic Fibrosis Canada, Diabetes Canada, Fondation Francophone pour la Recherche en Diabète (FFRD) , JDRF, National Institutes of Health, Société Francophone du Diabète (SFD) , Speaker's Bureau; Canadian Medical & Surgical Knowledge Translation Research Group (CMS) , CPD Network, Tandem Diabetes Care, Inc.


National Institutes of Health (1DP3DK106930-01)

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