Feasibility study of a combined insulin‐delivery and glucose sensor system worn over 7 days in persons with type 1 diabetes

Aims We aimed to evaluate sensor accuracy and insulin delivery integrity of a novel device combining continuous glucose monitoring (CGM) with an insulin delivering cannula (CGM‐IS) (Pacific Diabetes Technologies, Portland, Oregon, USA) during 7‐day wear, in adults with type 1 diabetes (T1D). Materials and Methods This single centre, single arm, non‐randomised study involves 40 T1D adults who were using insulin pumps and CGM for 7 days, with three meal test days and four free living days. The main endpoints were sensor accuracy according to mean average relative difference (MARD) and infusion set function reflected by time in range (TIR), mean sensor glucose and total daily dose (TDD) of insulin. Results Sensor MARD was 16.4%, 14.8% and 17.7% on Days 1, 4 and 7, respectively. 60.0% of readings met the 15/15 criterion for blood glucose (BG) readings <70.2 mg/dL. Insulin delivery integrity was maintained to Day 3. At Days 5–6 TDD increased by 7.3 units/day (16%), mean BG increased by 16.2 mg/dL (10.2%), and TIR fell by −7.8% (11.2%). 92.1% of devices lasted >4 days. Mean wear time was 6.3 ± 1.4 days. The device was well tolerated. Conclusion This human feasibility study supports the potential of CGM‐IS use for up to 7 days with a mean survival of over 6 days. However, our data indicate that the durability of insulin delivery and sensor refinement are required prior to commercialisation.