Abstract
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 \textpm 7.6 vs 25.6 \textpm 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 \textpm 11.0 vs 190.0 \textpm 31.0 ( P = .004) and 65.7 \textpm 9.2 vs 43.9 \textpm 14.7 ( P = .001), respectively. Superiority of glucose control with IP insulin came from the reduced time spent in hyperglycaemia (\textgreater180 mg/dL: 32.4 \textpm 8.9 vs 53.5 \textpm 17.4, P = .014; \textgreater250 mg/dL: 5.9 \textpm 5.6 vs 23.0 \textpm 11.3, P = .0004). Higher daily doses of insulin (IU) were delivered with the IP route (43.7 \textpm 0.1 vs 32.3 \textpm 0.1, P \textless .001) with no increased percent time spent \textless70 mg/dL (IP: 2.5 \textpm 2.9 vs SC: 4.1 \textpm 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.