Intraperitoneal insulin delivery provides superior glycaemic regulation to subcutaneous insulin delivery in model predictive control-based fully-automated artificial pancreas in patients with type 1 diabetes: a pilot study

Aims: To compare intraperitoneal (IP) to subcutaneous (SC) insulin delivery in an artificial pancreas (AP). Research design and methods: Ten adults with type 1 diabetes participated in a non-randomized, non-blinded sequential AP study using the same SC glucose sensing and Zone Model Predictive Control (ZMPC) algorithm adjusted for insulin clearance. On first admission, subjects underwent closed-loop control with SC delivery of a fast-acting insulin analogue for 24 hours. Following implantation of a DiaPort IP insulin delivery system, the identical 24-hour trial was performed with IP regular insulin delivery. The clinical protocol included 3 unannounced meals with 70, 40 and 70 g carbohydrate, respectively. Primary endpoint was time spent with blood glucose (BG) in the range of 80 to 140 mg/dL (4.4-7.7 mmol/L). Results: Percent of time spent within the 80 to 140 mg/dL range was significantly higher for IP delivery than for SC delivery: 39.8 7.6 vs 25.6 +/- 13.1 (P = .03). Mean BG (mg/dL) and percent of time spent within the broader 70 to 180 mg/dL range were also significantly better for IP insulin: 151.0 +/- 11.0 vs 190.0 +/- 31.0 (P = .004) and 65.7 +/- 9.2 vs 43.9 +/- 14.7 (P = .001), respectively. Superiority of glucose control with IP insulin came from the reduced time spent in hyperglycaemia (>180 mg/dL: 32.4 +/- 8.9 vs 53.5 +/- 17.4, P = .014; >250 mg/dL: 5.9 +/- 5.6 vs 23.0 +/- 11.3, P = .0004). Higher daily doses of insulin (IU) were delivered with the IP route (43.7 +/- 0.1 vs 32.3 +/- 0.1, P < .001) with no increased percent time spent <70 mg/dL (IP: 2.5 +/- 2.9 vs SC: 4.1 +/- 5.3, P = .42). Conclusions: Glycaemic regulation with fully-automated AP delivering IP insulin was superior to that with SC insulin delivery. This pilot study provides proof-of-concept for an AP system combining a ZMPC algorithm with IP insulin delivery.