Safety and Efficacy of 24-H Closed-Loop Insulin Delivery in Well-Controlled Pregnant Women With Type 1 Diabetes

A randomized crossover case series

  1. Roman Hovorka, PHD1,2
  1. 1Metabolic Research Laboratories and the National Institute for Health Research Cambridge Biomedical Research Center, University of Cambridge, Cambridge, U.K.
  2. 2Department of Pediatrics, University of Cambridge, Cambridge, U.K.
  3. 3Cambridge University Hospitals National Health Service Foundation Trust, Addenbrooke’s Hospital, Cambridge, U.K.
  4. 4Kings College Hospital, Guys, Kings, and St. Thomas’, London, U.K.
  1. Corresponding author: Helen R. Murphy, hm386{at}


OBJECTIVE To evaluate the safety and efficacy of closed-loop insulin delivery in well-controlled pregnant women with type 1 diabetes treated with continuous subcutaneous insulin infusion (CSII).

RESEARCH DESIGN AND METHODS A total of 12 women with type 1 diabetes (aged 32.9 years, diabetes duration 17.6 years, BMI 27.1 kg/m2, and HbA1c 6.4%) were randomly allocated to closed-loop or conventional CSII. They performed normal daily activities (standardized meals, snacks, and exercise) for 24 h on two occasions at 19 and 23 weeks’ gestation. Plasma glucose time in target (63–140 mg/dL) and time spent hypoglycemic were calculated.

RESULTS Plasma glucose time in target was comparable for closed-loop and conventional CSII (81% [59–87] vs. 81% [54–90]; P = 0.75). Less time was spent hypoglycemic (<45 mg/dL [0.0 vs. 0.3%]; P = 0.04), with a lower low blood glucose index (2.4 [0.9–3.5] vs. 3.3 [1.9–5.1]; P = 0.03), during closed-loop insulin delivery.

CONCLUSIONS Closed-loop insulin delivery was as effective as conventional CSII, with less time spent in extreme hypoglycemia.

  • Received July 29, 2011.
  • Accepted September 21, 2011.

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