Abstract

Objective: The most promising beta-cell replacement therapy for children with type 1 diabetes is a “closed-loop” (CL) artificial pancreas incorporating continuous glucose sensors and insulin pumps. The Medtronic MiniMed ePID System combines an external pump and sensor with a variable insulin infusion rate algorithm designed to emulate the physiological characteristics of the β-cell. However, delays in insulin absorption associated with subcutaneous route of delivery inevitably lead to large post-prandial glucose excursions.

Research Design and Methods: We studied the feasibility of the Medtronic ePID system in youth with type 1 diabetes and hypothesized that small manual pre-meal “priming” boluses would reduce post-prandial excursions during CL control. 17 adolescents (age 15.9± 1.6 y, A1c 7.1± 0.8%) underwent 34 hours of closed-loop (CL) control; 8 with full CL control (FCL), and 9 with “hybrid” CL (pre-meal priming bolus, HCL).

Results: Mean glucose levels were 135± 45 mg/dL in the HCL group vs. 141± 55 mg/dL in the FCL group (p=0.09); day-time glucose levels averaged 149± 47 mg/dL in the HCL group vs. 159± 59 mg/dL in the FCL group (p=0.03). Peak post-prandial glucose levels averaged 194± 47 mg/dL in the HCL group, vs. 226± 51 mg/dL in the FCL group (p=0.04). Night-time control was similar in both groups (111± 27 vs. 112± 28 mg/dL).

Conclusions: CL glucose control using an external sensor and insulin pump provides a means to achieve near normal glucose concentrations in youth with type 1 diabetes during the overnight period. The addition of small manual “priming” bolus doses of insulin, given 15 min before meals, improves post-prandial glycemic excursions.