Background: Carb-counting is a significant burden for persons with diabetes who require insulin to mitigate postprandial hyperglycemia. A closed-loop (CL) system with auto meal-bolus that eliminates manual mealtime bolusing was studied in adults with T1D. Methods: The system included the MiniMed™ 780G pump and a smartphone-paired smartwatch with the KLUE application that detects eating hand-gestures using motion sensors. A smartphone algorithm converted eating hand-gestures to carb amounts that were relayed to the pump for automatic bolusing. For 6 days, participants (N=17, aged 18-75 years) with T1D used the system with the KLUE app disabled and completed traditional carb-counting and -entry (Baseline) . Thereafter, the KLUE app was enabled for 5 days and carb-counting/carb-entry was prohibited (Study) . Participants were given the same 5 test-meals (one/day) of varying caloric and carb sizes during both periods. Otherwise, they had no other meal restrictions. Results: No significant difference in TIR was observed between periods and time spent at <70 mg/dL was significantly less during the Study period (Table) . Conclusion: Data suggest that the novel CL system maintains glycemic control similar to that with manual meal bolusing. By eliminating the burden of carb-counting, the new CL system may improve the quality of life in persons with T1D. Disclosure A.Roy: Employee; Medtronic. A.Tirosh: Advisory Panel; Abbott Diagnostics, AstraZeneca, Boehringer Ingelheim International GmbH, Merck & Co., Inc., Novo Nordisk, Sanofi, Consultant; Bayer AG, DreaMed Diabetes, Ltd., Research Support; Medtronic, Speaker's Bureau; Eli Lilly and Company. B.Grosman: Employee; Medtronic. D.Miller: Employee; Medtronic. T.Engel: None. O.Cohen: Employee; Medtronic. R.Shalit: Speaker's Bureau; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Medtronic, Novo Nordisk. S.Shalem: None. M.Laron hirsh: None. Y.Cohen: None.

Background and Aims: Meal management is a major challenge for people with type 1 diabetes (PWD) . We aimed to explore 3 approaches to complex meal planning, from a most comprehensive scheme in open loop (OL) to a simplified, carbohydrate (CHO) counting-free scheme when using the MiniMed™ 780G system AHCL. Methods: Participants (N=13, mean age 46.8±12.8 years and baseline A1C of 6.1±1.2%) consumed a high fat, high protein, meal using 3 types of insulin boluses;1) OL utilizing the dual-wave bolus and elaborate CHO counting;2) AHCL with accurate CHO amount;3) AHCL with a predefined bolus and no CHO counting, Results: No significant differences in TIR and 5-hour iAUC were observed between the 3 bolus groups (P=0.401, P=0.526, respectively) There were no significant differences in other glucose metrics. (Table 1) Conclusion: Our results indicate that glycemic control following a complex meal challenge is similar when using AHCL with or without accurate CHO counting and with less tendency for hypoglycemia when compared with the most elaborate meal management in OL. Thus, the current burden of meal management for PWD during OL system use is alleviated with AHCL. Disclosure M.Laron hirsh: None. R.Shalit: Speaker's Bureau; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Medtronic, Novo Nordisk. S.Shalem: None. O.Cohen: Employee; Medtronic. N.Kurtz: Employee; Medtronic. A.Roy: Employee; Medtronic. B.Grosman: Employee; Medtronic. T.Cukierman-yaffe: Research Support; European Association for the Study of Diabetes, Medtronic, Merck Sharp & Dohme Corp., Novo Nordisk, Speaker's Bureau; AstraZeneca, Eli Lilly and Company, Medtronic, Merck Sharp & Dohme Corp., Novo Nordisk, Sanofi. A.Tirosh: Advisory Panel; Abbott Diagnostics, AstraZeneca, Boehringer Ingelheim International GmbH, Merck & Co., Inc., Novo Nordisk, Sanofi, Consultant; Bayer AG, DreaMed Diabetes, Ltd., Research Support; Medtronic, Speaker's Bureau; Eli Lilly and Company.

Background: We compared glycemic outcomes and participant experience during MiniMed™ 780G Advanced Hybrid Closed Loop (AHCL) system use while announcing all meals vs. announcing meals at will. Methods: Participants with T1DM used the AHCL system at home during two 90 days phases in which they were given instructions first to announce all meals (AM) , and next, for meals containing up to 80 grams of carbohydrates, to announce meals at will (AMW) . Results: Fourteen subjects (males, mean age 44.3±11) with T1DM were enrolled, with a baseline A1C of 6.9±1%. Table 1 summarizes glycemic indices and AHCL data, demonstrating that patients chose to bolus only slightly less during AMW compared to AM (5.5 vs. 5.2 boluses) , without resultant deterioration in glycemic indices (A1c 6.4 vs. 6.5%, TIR 78.1 vs. 78.8%, p=ns) . Subjects surveyed regarding the option not to have to bolus for all meals experienced a significant reduction in reported effort to manage diabetes (p=0.045) and 86% endorsed worrying less about their diabetes. Most (93%) preferred the AMW phase of the study. Conclusion: The MinMed™ AHCL system is designed for optimal performance with meal announcement. Nonetheless, when meals containing < 80 grams of carbohydrates are consumed with announcement of meals at will, there is a slight reduction in the number of daily boluses with no decline in glycemic control, yet markedly less diabetes related distress and improved treatment satisfaction. Disclosure N. Minsky: None. R. Shalit: Speaker's Bureau; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Medtronic, Novo Nordisk. O. Cohen: Employee; Medtronic. N. Kurtz: Employee; Medtronic. A. Roy: Employee; Medtronic. B. Grosman: Employee; Medtronic. A. Tirosh: Advisory Panel; Abbott Diagnostics, AstraZeneca, Boehringer Ingelheim International GmbH, Merck & Co., Inc., Novo Nordisk, Sanofi. Consultant; Bayer AG, DreaMed Diabetes, Ltd. Research Support; Medtronic. Speaker's Bureau; Eli Lilly and Company.