Day-and-night closed-loop insulin delivery in pregnancy

Stewart ZA, Wilinska ME, Hartnell S et al (2018) Day-and-night closed-loop insulin delivery in a broad population of pregnant women with type 1 diabetes: a randomized controlled crossover trial. Diabetes Care 41: 1391–9

• This open-label, randomised, two-period crossover trial evaluated the safety and efficacy of the Florence D2A, the fully closed-loop insulin system under development at the University of Cambridge.
• A total of 16 pregnant women with type 1 diabetes, with gestational age between 8 and 24 weeks, were randomised to day-and-night use of either sensor-augmented pump (SAP) therapy or the closed-loop system for 4 weeks, before switching to the other therapy after a 1–2-week washout period. NICE-recommended blood glucose targets were used and there were not restrictions on diet, exercise or travel, and no remote monitoring took place.
• The results showed no difference in the amount of time spent in the target glycaemic range between closed-loop and SAP therapy (62.3% vs 60.1%). There were also no differences in mean blood glucose, time spent in hyperglycaemia or HbA_1c.
• However, there were fewer episodes of hypoglycaemia (blood glucose <3.5 mmol/L) in the closed-loop arm (median 8.0 vs 12.5; P=0.04), and less time was spent hypoglycaemic (1.6% vs 2.7%). There were no episodes of severe hypoglycaemia in either group.
• No serious adverse events occurred, but there were often device malfunctions in the closed-loop arm. Despite this, all participants chose to continue using the device for at least some time after the trial ended (the device was offered up to 6 weeks postpartum). During this period, the median time in target range was around 70%.
• Some individual variation in response to the closed-loop system was observed, with five participants (31%) having worse glycaemic control whilst on the intervention. Despite this, these participants elected to continue using the closed-loop system after the trial.
• Regarding neonatal outcomes, the participants delivered at a median gestation of 36.9 weeks, 13 by caesarean section. Eleven infants (69%) were admitted to intensive care, seven of whom (44%) were treated for hypoglycaemia. Seven infants (44%) were large for gestational age. Two infants had congenital abnormalities.
• The authors conclude that day-and-night closed-loop insulin delivery was effective in pregnant women with type 1 diabetes, and potentially safer as it was associated with less hypoglycaemia that SAP therapy. Larger, longer-duration trials are planned.

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