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Closed-loop basal insulin delivery over 36 hours in adolescents with type 1 diabetes: randomized clinical trial.

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Elleri, Daniela 
Allen, Janet M 
Kumareswaran, Kavita 
Leelarathna, Lalantha 


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.



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

Journal Title

Diabetes Care

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American Diabetes Association
National Institute of Diabetes and Digestive and Kidney Diseases (R01DK085621)
Diabetes UK (None)
TCC (None)
Cambridge University Hospitals NHS Foundation Trust (CUH) (Roman Hovorka)
Medical Research Council (G0600717)
TCC (None)
Medical Research Council (MC_UU_12012/5)
Medical Research Council (MC_PC_12012)
Medical Research Council (G0600717/1)