Hyperglycemia can increase the risk of stillborn pregnancies among women with type 1 diabetes, and also increases maternal mortality. While there has so far been little evidence to support the routine use of an artificial pancreas during pregnancy, a 25 per cent reduction in hyperglycemia could significantly reduce the risk of complications during and after pregnancy for both mother and child.
This study examined the success of a “closed-loop” insulin delivery system, which connects an insulin pump and a continuous glucose monitor (CGM). An algorithm then works on a device, such as a smartphone, to calculate a patient’s insulin delivery.
Dr. Zoe Stewart, University of Cambridge, told the Diabetes UK 2016 Professional Conference that her team’s previous research found an artificial pancreas can control blood glucose levels efficienty in patients with type 1 diabetes during early and late pregnancy. These studies were conducted “under closely supervised inpatient conditions”.
In this new study, 16 women aged between 16 and 44 years were randomised to one of two groups. The first group received sensor-augmented insulin-pump therapy; the second received sensor-augmented insulin-pump therapy with CGM to create the closed loop at night for 28 nights. The women participants had type 1 diabetes for an average of 23 years and were between eight to 20 weeks pregnant.
This experiment was to determine the impact of overnight closed-loop insulin delivery in a real-life home setting.
Two weeks after the first intervention finished, the participants then completed the opposite intervention treatment. At the end of this second trial, participants could choose to continue with whatever components of the system they wanted to use for the duration of their pregnancy.
Women who used the artificial pancreas had a 25 per cent relative improvement in the time they spent with their blood glucose levels between 3.5 mmol/l and 7.8 mmol/l overnight. Women in this group also had less hyperglycemia and had an improved reduction in mean glucose overnight. There was no difference between the groups in total daily insulin dose or events of hypoglycemia.
14 of the 17 women continued to use the artificial pancreas up until the birth and in some cases immediately after the birth. This was done without any safety problems.
Stewart said: “Overnight home closed-loop [delivery] appears to be safe and effective in pregnancy; it may be able to reduce hyperglycemia in the order of about 25 per cent … without increasing hypoglycemia and without increasing insulin dose.”
“These results are consistent with studies in children, adolescents, and adults,” added Stewart, whose team are now comparing 24/7 use of the closed-loop system with pump use in a further 16 pregnant women with type 1 diabetes.