2808-LB: A Qualitative Analysis of Factors Influencing Glycaemia among Adult Users of Hybrid Closed-Loop Insulin Delivery in Type 1 Diabetes

Introduction and Objective: We explored experiences of hybrid closed-loop (HCL) insulin delivery among adults with type 1 diabetes (T1D) to identify factors shaping user-system interactions that may influence glycaemia. Methods: Semi-structured interviews among adults with baseline time in range (TIR;3.9-10 mmol/L) <60% and change in TIR ≥10% and <10% post-HCL start. Results: 19 individuals participated (62% female, median age 47 years [36,54]; median diabetes duration 24 years [19,34]; 10 with ≥10% and 9 with <10% change in TIR). Results reflect subgroup analyses. Participants with ≥10% TIR change often reported a desire for “perfect” glycaemia and hyperglycaemia aversion driven by personality traits and fear of complications. Many prioritised diabetes over coexisting life priorities, without perceiving this as limiting. Most described established routines with pre-bolusing mealtime insulin and confident carbohydrate counting, often reporting confidence in reviewing HCL data and adjusting insulin delivery settings. Despite challenges with alarm and data burden, most described HCL as transformative and a “supportive friend”. Participants with <10% TIR change generally acknowledged HCL benefits, but ongoing cognitive and practical demands limited trust. Many expressed a lack of confidence in reviewing insulin delivery data and carbohydrate counting, with conflicting life priorities limiting engagement with technology. Hyperglycaemia aversion and past experiences of severe hypoglycaemia continued to shape interactions with HCL, sometimes prompting overcorrection, insulin under-delivery, or physical detachment from insulin pump “the panic comes, I don’t want to go into a coma..that’s when I take it off”. Conclusion: Glycaemia with HCL use results from interactions across behavioural, psychosocial, and technical factors. Ongoing analyses aim to inform personalised educational and support initiatives and technological improvements to enable equitable and sustainable benefits. Disclosure A. Anandhakrishnan: None. C. Woombs: None. M. Holloway: Research Support; Current; Dexcom, Inc. Consultant; Ended; Insulet Corporation, Children with Diabetes, Inc. K. Barnard-Kelly: Research Support; Current; Abbott Diabetes, Dexcom, Inc. S. Hussain: Advisory Panel; Ended; Medtronic. Speaker's Bureau; Ended; Dexcom, Inc., Abbott, Insulet Corporation. Advisory Panel; Ended; Tandem Diabetes Care, Inc. Speaker's Bureau; Ended; Lilly. Consultant; Ended; Roche Diabetes Care.