Closed-Loop Insulin Delivery During Pregnancy Complicated by Type 1 Diabetes

  1. Roman Hovorka, PHD1,2
  1. 1Institute of Metabolic Science, Metabolic Research Laboratories, University of Cambridge, Hills Road, Cambridge, U.K.
  2. 2Department of Paediatrics, University of Cambridge, Hills Road, Cambridge, U.K.
  3. 3Institute of Metabolic Science, Cambridge University Hospitals NHS Foundation Trust, Cambridge, U.K.
  4. 4Diabetes Centre, Ipswich Hospital NHS Trust, Ipswich, U.K.
  5. 5Elsie Bertram Diabetes Centre, Norfolk and Norwich University Hospital NHS Trust, Norwich, U.K.
  1. Corresponding author: Helen R. Murphy, hm386{at}


OBJECTIVE This study evaluated closed-loop insulin delivery with a model predictive control (MPC) algorithm during early (12–16 weeks) and late gestation (28–32 weeks) in pregnant women with type 1 diabetes.

RESEARCH DESIGN AND METHODS Ten women with type 1 diabetes (age 31 years, diabetes duration 19 years, BMI 24.1 kg/m2, booking A1C 6.9%) were studied over 24 h during early (14.8 weeks) and late pregnancy (28.0 weeks). A nurse adjusted the basal insulin infusion rate from continuous glucose measurements (CGM), fed into the MPC algorithm every 15 min. Mean glucose and time spent in target (63–140 mg/dL), hyperglycemic (>140 to ≥180 mg/dL), and hypoglycemic (<63 to ≤50 mg/dL) were calculated using plasma and sensor glucose measurements. Linear mixed-effects models were used to compare glucose control during early and late gestation.

RESULTS During closed-loop insulin delivery, median (interquartile range) plasma glucose levels were 117 (100.8–154.8) mg/dL in early and 126 (109.8–140.4) mg/dL in late gestation (P = 0.72). The overnight mean (interquartile range) plasma glucose time in target was 84% (50–100%) in early and 100% (94–100%) in late pregnancy (P = 0.09). Overnight mean (interquartile range) time spent hyperglycemic (>140 mg/dL) was 7% (0–40%) in early and 0% (0–6%) in late pregnancy (P = 0.25) and hypoglycemic (<63 mg/dL) was 0% (0–3%) and 0% (0–0%), respectively (P = 0.18). Postprandial glucose control, glucose variability, insulin infusion rates, and CGM sensor accuracy were no different in early or late pregnancy.

CONCLUSIONS MPC algorithm performance was maintained throughout pregnancy, suggesting that overnight closed-loop insulin delivery could be used safely during pregnancy. More work is needed to achieve optimal postprandial glucose control.

  • Received September 17, 2010.
  • Accepted October 27, 2010.

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  1. Diabetes Care
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