Closed-loop insulin delivery success in pregnancy
medwireNews: Overnight closed-loop insulin delivery maintains tighter control of glucose levels than sensor-augmented pump delivery in pregnant women with Type 1 diabetes, shows a randomised crossover trial.
Helen Murphy (University of Cambridge, UK) and study co-authors stress the importance of their findings, given the rapid changes in insulin requirements and resistance during pregnancy and delivery. “Previous outpatient studies of closed-loop therapy have focused on relatively steady-state diabetes in the absence of pregnancy”, they write in The New England Journal of Medicine.
The 16 study participants were at an average 14 weeks’ gestation at baseline. During the 4-week control phase, when the women used overnight sensor-augmented pump therapy, their overnight glucose levels were within target range (63–140 mg/dL) 59.5% of the time.
The team notes that, despite the challenges of pregnancy, this level of control is “similar to that achieved with closed-loop interventions among patients who were not pregnant”, which is probably a result of “the strong motivation to maintain glucose control during pregnancy”.
Yet closed-loop delivery still produced a significant 15.2 percentage point improvement, with women being within target levels 74.7% of the time during this 4-week period. The women undertook the control and closed-loop phases in a randomised order, with a 2-week washout period between.
Average glucose levels during the control and closed-loop phases were 119 versus 133 mg/dL overnight and 128 versus 137 mg/dL over 24 hours. And this reduced glucose level did not come at the expense of more hypoglycaemia, with no differences between the treatment periods in time spent below the target range.
Only two participants had previous experience of sensor-augmented pumps, and six had never used any type of insulin pump. However, all patients underwent a training and dose optimisation period of 2 to 4 weeks, and glycaemic control during the study was unaffected by previous pump use.
In a feasibility study after the randomised period, 14 patients opted to use 24-hour closed-loop insulin delivery for the remainder of their pregnancies (median 11.6 weeks). Their glucose levels remained within target levels for 68.7% of the time overall, 86.8% of the time during the 24 hours before delivery and 73.7% of the time during the first 48 hours after delivery.
Despite the good maternal glycaemic control, 13 infants had a birthweight that was above the 90th percentile for their gestational age and, of the 12 who required intensive care after birth, 11 were treated for hypoglycaemia.
“Fetal hyperinsulinemia and increased placental fuel transfer can persist with apparently normal maternal glycemia and may in part explain these outcomes”, say Murphy et al. “Larger trials of closed-loop therapy for a longer period are needed to evaluate the effects of this therapy on obstetrical and neonatal outcomes.”
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