LAUSR

Carbohydrate counting to quantify prandial insulin requirement remains a key aspect of type 1 diabetes self-management. This, however, remains challenging, leading to dysglycaemia and increased burden for many people with type 1 diabetes. Current hybrid closedloop systems still require manual meal (prandial) bolusing due to the relatively slow action of standard rapid-acting insulin. There is a need to reduce the burden of carbohydrate counting by improving the effectiveness of closed-loop systems, potentially with the use of ultra-rapid-acting insulin analogues. Pharmacokinetic and pharmacodynamic studies have shown that faster-acting insulin aspart administration is associated with earlier insulin exposure and action, and earlier offset of exposure compared to standard insulin aspart. Studies with hybrid closed-loop systems under various conditions have shown mixed results. We aimed to evaluate whether faster-acting insulin aspart will improve glucose control compared to insulin aspart using the CamAPS FX closed-loop system (CamDiab, Cambridge, UK), under conditions mimicking underestimation of meal carbohydrate content or missed meal bolus.