Closed-loop basal insulin delivery over 36 hours in adolescents with type 1 diabetes

Daniela Elleri, Janet M Allen, Kavita Kumareswaran, Lalantha Leelarathna, Marianna Nodale, Karen Caldwell, Peiyao Cheng, Craig Kollman, Ahmad Haidar, Helen R Murphy, Malgorzata E Wilinska, Carlo L Acerini, David B Dunger, Roman Hovorka

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137 Citations (Scopus)


OBJECTIVE: We evaluated the safety and efficacy of closed-loop basal insulin delivery during sleep and after regular meals and unannounced periods of exercise.

RESEARCH DESIGN AND 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.

Original languageEnglish
Pages (from-to)838-344
Number of pages7
JournalDiabetes Care
Issue number4
Publication statusPublished - Apr 2013


  • Adolescent
  • Child
  • Diabetes Mellitus, Type 1
  • Female
  • Humans
  • Hypoglycemic Agents
  • Insulin
  • Insulin Infusion Systems
  • Male

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