title: Closed-loop basal insulin delivery over 36 hours in adolescents with type 1 diabetes: randomized clinical trial.
abstract: OBJECTIVE
  We evaluated the safety and efficacy of closed-loop basal insulin delivery during sleep and after regular meals and unannounced periods of exercise.
  
  
  METHODS
  Twelve adolescents with type 1 diabetes (five males; mean age 15.0 [SD 1.4] years; HbA1c 7.9 [0.7]%; BMI 21.4 [2.6] kg/m(2)) were studied at a clinical research facility on two occasions and received, in random order, either closed-loop basal insulin delivery or conventional pump therapy for 36 h. During closed-loop insulin delivery, pump basal rates were adjusted every 15 min according to a model predictive control algorithm informed by subcutaneous sensor glucose levels. During control visits, subjects' standard infusion rates were applied. Prandial insulin boluses were given before main meals (50-80 g carbohydrates) but not before snacks (15-30 g carbohydrates). Subjects undertook moderate-intensity exercise, not announced to the algorithm, on a stationary bicycle at a 140 bpm heart rate in the morning (40 min) and afternoon (20 min). Primary outcome was time when plasma glucose was in the target range (71-180 mg/dL).
  
  
  RESULTS
  Closed-loop basal insulin delivery increased percentage time when glucose was in the target range (median 84% [interquartile range 78-88%] vs. 49% [26-79%], P = 0.02) and reduced mean plasma glucose levels (128 [19] vs. 165 [55] mg/dL, P = 0.02). Plasma glucose levels were in the target range 100% of the time on 17 of 24 nights during closed-loop insulin delivery. Hypoglycemia occurred on 10 occasions during control visits and 9 occasions during closed-loop delivery (5 episodes were exercise related, and 4 occurred within 2.5 h of prandial bolus).
  
  
  CONCLUSIONS
  Day-and-night closed-loop basal insulin delivery can improve glucose control in adolescents. However, unannounced moderate-intensity exercise and excessive prandial boluses pose challenges to hypoglycemia-free closed-loop basal insulin delivery.
authors.affiliation: Department of Paediatrics, University of Cambridge, Cambridge, UK.
authors.forename: Daniela
authors.initials: D
authors.lastname: Elleri
authors.forename: Janet M
authors.initials: JM
authors.lastname: Allen
authors.forename: Kavita
authors.initials: K
authors.lastname: Kumareswaran
authors.forename: Lalantha
authors.initials: L
authors.lastname: Leelarathna
authors.forename: Marianna
authors.initials: M
authors.lastname: Nodale
authors.forename: Karen
authors.initials: K
authors.lastname: Caldwell
authors.forename: Peiyao
authors.initials: P
authors.lastname: Cheng
authors.forename: Craig
authors.initials: C
authors.lastname: Kollman
authors.forename: Ahmad
authors.initials: A
authors.lastname: Haidar
authors.forename: Helen R
authors.initials: HR
authors.lastname: Murphy
authors.forename: Malgorzata E
authors.initials: ME
authors.lastname: Wilinska
authors.forename: Carlo L
authors.initials: CL
authors.lastname: Acerini
authors.forename: David B
authors.initials: DB
authors.lastname: Dunger
authors.forename: Roman
authors.initials: R
authors.lastname: Hovorka
mesh_terms: D000293:Adolescent; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000627:therapeutic use*; D007328:Insulin / Q000008:administration & dosage* / Q000627:therapeutic use*; D007332:Insulin Infusion Systems; D008297:Male
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin