FiASP vs. aspart using an advanced closed-loop system

This randomised crossover study compares glucose control using an advanced hybrid closed-loop (A-HCL) system delivering faster acting insulin aspart (FiASP) vs. insulin aspart in adults with type 1 diabetes. FiASP has a more rapid onset and shorter duration of insulin action, therefore may improve the responsive of a HCL system. There is limited data available regarding the use of FiASP in HCL systems. Participants will be assigned in random order either FiASP or insulin aspart delivery for a six week duration each via the A-HCL system (Stage 1 and Stage 2). Stage 1 and Stage 2 will be separated by two weeks, during which the insulin assigned for Stage 2 will be delivered in open-loop (OL). Two meal interventions (missed meal bolus and delayed meal bolus) will be conducted each during both Stage 1 and 2, incorporating a 40g carbohydrate-containing meal at home for dinner. For the final week of the study (Stage 3), participants will revert to the insulin that they were assigned to in Stage 1 without a wash-out period in OL. This study will consist of ~5 visits over approximately a period of ~17 weeks. All participants will be provided with study devices and receive education regarding their use. The HCL system has advanced closed-loop (CL) capability. It comprises a continuous glucose monitoring (CGM) device ie. glucose sensor with a small electrode placed under the skin to continuously measure interstitial glucose levels, coupled with an insulin pump containing a computerised automated insulin delivery algorithm. Glucose sensor information is transmitted to the insulin pump, and the dose of insulin is calculated by the algorithm and automatically delivered every 5 minutes to account for basal insulin requirements. Patient-initiated bolus insulin doses are still required for meals. Twenty-four participants are planned to undertake the study at one clinical site. All procedures involving study participants will be undertaken by study doctors and research nurses. Participants will receive regular text message and phone call reminders during each stage of the study to ensure adherence.