title: Fully automated closed-loop insulin delivery versus semiautomated hybrid control in pediatric patients with type 1 diabetes using an artificial pancreas.
abstract: OBJECTIVE
  The most promising beta-cell replacement therapy for children with type 1 diabetes is a closed-loop artificial pancreas incorporating continuous glucose sensors and insulin pumps. The Medtronic MiniMed external physiological insulin delivery (ePID) system combines an external pump and sensor with a variable insulin infusion rate algorithm designed to emulate the physiological characteristics of the beta-cell. However, delays in insulin absorption associated with the subcutaneous route of delivery inevitably lead to large postprandial glucose excursions.
  
  
  METHODS
  We studied the feasibility of the Medtronic ePID system in youth with type 1 diabetes and hypothesized that small manual premeal "priming" boluses would reduce postprandial excursions during closed-loop control. Seventeen adolescents (aged 15.9 +/- 1.6 years; A1C 7.1 +/- 0.8%) underwent 34 h of closed-loop control; 8 with full closed-loop (FCL) control and 9 with hybrid closed-loop (HCL) control (premeal priming bolus).
  
  
  RESULTS
  Mean glucose levels were 135 +/- 45 mg/dl in the HCL group versus 141 +/- 55 mg/dl in the FCL group (P = 0.09); daytime glucose levels averaged 149 +/- 47 mg/dl in the HCL group versus 159 +/- 59 mg/dl in the FCL group (P = 0.03). Peak postprandial glucose levels averaged 194 +/- 47 mg/dl in the HCL group versus 226 +/- 51 mg/dl in the FCL group (P = 0.04). Nighttime control was similar in both groups (111 +/- 27 vs. 112 +/- 28 mg/dl).
  
  
  CONCLUSIONS
  Closed-loop 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 postprandial glycemic excursions.
authors.affiliation: Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520-8064, USA. stuart.weinzimer@yale.edu
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Weinzimer
authors.forename: Garry M
authors.initials: GM
authors.lastname: Steil
authors.forename: Karena L
authors.initials: KL
authors.lastname: Swan
authors.forename: Jim
authors.initials: J
authors.lastname: Dziura
authors.forename: Natalie
authors.initials: N
authors.lastname: Kurtz
authors.forename: William V
authors.initials: WV
authors.lastname: Tamborlane
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001187:Artificial Organs; D001331:Automation; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy*; D004040:Dietary Carbohydrates; D004867:Equipment Design; D006801:Humans; D007003:Hypoglycemia / Q000517:prevention & control; D007328:Insulin / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use*; D007332:Insulin Infusion Systems; D007515:Islets of Langerhans / Q000033:anatomy & histology*; D010179:Pancreas
chemical_list: D004040:Dietary Carbohydrates; D007328:Insulin