Faster insulin aspart (FiASP) vs. apart using an advanced closed-loop system: Extension study evaluating meal-time glucose control

An extension to the study ACTRN12619000469112. This is a crossover study comparing 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 when challenged with different meal interventions. 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 particularly with varying meal sizes, composition and time of day. The study will have 2 stages. During Stage 1 of this study, all participants will be infusing insulin aspart via the A-HCL system for a 11 week period. Meal challenges will be administered in a free living environment twice a week with compositions varying in terms of carbohydrate content (30 or 60g) and high or low glycaemic index and protein content. Participants will be asked to bolus insulin immediately prior to meals. Insulin boluses will vary between correct dose boluses and modified to under-dose. Upon completion of Stage 1, there will be washout period of 1 week. All participants will then enter Stage 2 whereby FiASP will be infused via A-HCL for a 11 week period during which study activities, including meal tests and meal bolus administration will mirror those in Stage 1. This study will consist of ~3 visits over a period of ~20 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. It is anticipated that all twelve participants recruited into the main study ACTRN12619000469112 will be recruited into this extension study which will be conducted 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.