Positive Outcomes for Closed-loop During Childbirth in T1D

Becky McCall

July 09, 2018

ORLANDO, USA - Pregnant women with type 1 diabetes who use an automated closed-loop insulin delivery system during labour, delivery and postpartum, spent over 80% of their time within the blood glucose target range, shows new data. This supports the potential role of closed-loop systems on delivery wards.

Professor Helen Murphy from Norwich Medical School at the University of East Anglia is a specialist researcher and clinician in diabetes and antenatal care. At the recent American Diabetes Association (ADA) 2018 Scientific Sessions, she updated delegates with the latest study data on use of continuous glucose monitoring (CGM) within a closed-loop system in pregnancy and during birth.

The analysis of closed-loop systems in labour and delivery drew on data from two prior studies in which pregnant women wore closed-loop systems (consisting of a CGM, an insulin pump, and a computer-controlled algorithm on either a tablet PC or a smartphone) throughout their pregnancy. "Unfortunately, when most women who use insulin pumps during pregnancy come in to give birth it's taken off them and they receive care from midwives who often have little experience of diabetes," explained Murphy. "But in our study, we gave women the choice to continue to wear the closed-loop throughout labour and after the birth," she said, adding that, "this allows midwives to focus on safe delivery of the baby, while the women had near perfect blood sugar control throughout."

Closed-loop During Delivery Helps Overworked Delivery Wards

A total of 27 of 32 women chose to retain their closed-loop system during labour  (defined as the 24 hours pre-delivery), delivery and the immediate postpartum period (48 hours after delivery). Delivery modes included vaginal, elective, and emergency caesarean sections. During labour and delivery, the time spent in the glucose target range was over 80%, with a mean glucose of 6.9 mmol/L (glucose target range during pregnancy was 3.5–7.8 mmol/L). The time spent above target was 16.0%. Hypoglycaemia was uncommon, and median time below target was 0%, although seven women (26.9%) had at least one hypoglycaemic event.

Postpartum [48 hours], women also spent over 80% of the time in range (defined as 3.9–10.0 mmol/L), with a mean glucose level of 7.2 mmol/L. There was minimal hyperglycaemia with a median of 9.1%, and the median number of hypoglycaemic events was 1.5. No severe hypoglycaemic events were seen.

Murphy highlighted the importance of the closed-loop system in responding to glucose levels upon delivery of the baby. "When the baby arrives, the closed-loop systems stopped delivering insulin, as soon as the mother's glucose levels start to drop. At this point, many women struggle with low glucose levels," she added.

"These are very strong results, and the women loved using the closed-loop – we struggled to get the systems back from them after they gave birth," Murphy remarked, emphasising how delivery ward staff also welcomed the opportunities offered by the technology.

"This could help save time and money on delivery wards, which are overworked with a national shortage of midwives, who are not trained to deal with the intensely demanding hourly glucose testing and insulin infusion adjustments," Murphy pointed out.

Closed-Loop in Pregnancy (CLIP)

At the ADA, Murphy also reported results of the day and night CLIP (Closed-Loop in Pregnancy) study, which was also published in the July edition of Diabetes Care.

"Closed-loop involves linking the CGM to the insulin pump, and uses a computer algorithm on a smart phone to automatically calculate the insulin dose every 10-15 minutes," Murphy explained, adding that, "this means women no longer have to do the calculations in their heads. It also means they can sleep with less worry about low glucose levels overnight. However, women are still required to inject prior to a meal."

There was no significant difference in overall day and night time-in-range (70-140 mg/dl) between closed-loop versus sensor-augmented pump (SAP) insulin delivery (62.3% versus 60.1% respectively). However, the closed-loop system did reduce the hypoglycaemic event rate at 8 versus 12.3 episodes in the closed loop and SAP groups (p=0.04), and there was also less nocturnal hypoglycaemia during closed-loop therapy 1.1% versus 2.7% (P = 0.008).

"Together these studies show that closed-loop has the potential to improve overnight glucose control, reduce the risk of hypoglycaemia and to be used effectively on labour and delivery units," said Murphy.

"In babies, hyperglycaemia causes complications, but for the mothers, hypoglycaemia can be a major challenge, so there's a fine balance to be struck between a mother obtaining the best glucose control for the baby without themselves having seriously low glucose levels."

CONCEPTT and Flash Glucose Monitoring System FreeStyle Libre 

Murphy also discussed results of using the intermittent or 'flash' glucose monitoring system (FreeStyle Libre, Abbott) as an alternative to CGM during pregnancy. CGM was used in the Continuous Glucose Monitoring in Pregnant Women with Type 1 Diabetes trial (CONCEPTT), but the flash monitoring system was trialled as an alternative and produced similar results, said Murphy. Results of CONCEPTT were reported by Medscape Medical News last year. These showed that using CGM compared to traditional finger-prick tests during pregnancy in type 1 diabetes lowered HbA1c, resulting in 100 minutes more time per day in the recommended target range (3.5–7.8mmol/L), and that the risk of large-for-gestational-age babies (>90th percentile weight) was approximately halved.

The FreeStyle Libre is considerably less expensive than CGM systems, at approximately £500 per complete pregnancy versus £1500 with CGM, according to Murphy.

"In effect, a small improvement for the mother results in a massive improvement for the babies," stressed Murphy. "This [flash system] cost is very comparable to that of the finger-prick test that they would have used previously, but they provide women with more information about glucose levels to help them administer insulin more precisely," she added.

NHS England has now recommended that CGM, including the flash FreeStyle Libre system, be offered to pregnant women with type 1 diabetes during the first trimester.

More recently the Dexcom G6 has introduced a very accurate, user friendly and affordable real-time CGM, which is accurate enough to replace pre-meal glucose testing.

Dr William Tamborlane, of Yale University, New Haven, in the US, was moderator of a session on using continuous glucose monitoring and smart devices to control glucose when it matters most. Commenting on Murphy's work, Tamborlane remarked that the researcher was one of the leaders in the application of advanced diabetes technologies in the management of diabetes in pregnancy. "Last year, Murphy's work on CGM greatly increased the time that glucose levels were in the target range in pregnant women with type 1 diabetes compared to standard blood glucose meter monitoring, and now we see that a hybrid, closed-loop system is even more effective than current treatment in managing glycaemia before, during and after delivery in women with T1D," he said. "Translation of use of such systems into regular clinical practice would allow midwives to more time and effort on the safe delivery of the baby."

'Significant Impact'

Medscape News UK asked Dr Peter Hammond, Consultant Endocrinologist, Harrogate District Hospital and Leeds GIS, to comment on this latest research. He said: "Despite advances in insulin management in people with diabetes, including new analogue insulins and wider uptake of insulin pump therapy, adverse outcomes of pregnancy for women with diabetes remain common, particularly neonatal problems such as large for gestational age babies and neonatal hypoglycaemia. There is increasing evidence that continuous glucose monitoring (CGM) during pregnancy for women with diabetes on intensive insulin regimens can have a significant impact on these outcomes, with the recently published CONCEPTT study showing that regular use of real time CGM by 6 women preventing one baby being large for gestational age, and by 8 women preventing one episode of neonatal hypoglycaemia.

"However, use of technologies such as insulin pump therapy and CGM, whilst effective in optimising blood glucose control, requires a great deal of effort from the pregnant woman, and this can often be quite burdensome. Automation of insulin delivery through a closed loop delivery system combining pump and CGM offers an effective way of achieving optimal glycaemic control without such a burden on the user. Professor Murphy and her team have shown that such a closed loop delivery system can be effectively deployed throughout pregnancy, including labour and the post-partum period, making optimal management of diabetes during pregnancy less burdensome for the mother and improving outcomes for the baby."

COI: Murphy declares the following: Advisory Panel; Self; Medtronic MiniMed, Inc.. Research Support; Self; Abbott. Tamborlane declared that he is a consultant for Medtronic Diabetes.

COI: Hammond received honoraria for speaking and Ad Board attendance from Medtronic, Roche and Abbott.

American Diabetes Association (ADA) 2018 Scientific Sessions. Presented as a poster June 24, 2018 - Adaptability of Closed-Loop during Labor, Delivery, and Postpartum—A Secondary Analysis of Data From Two Randomized Crossover Trials in Type 1 Diabetes Pregnancy. Abstract.

Abstract 1432-P. Presented June 23, 2018 - Intensive Glycemic Treatment during Pregnancy. Abstract.

Lancet. 2017 Nov 25;390(10110):2347-2359. doi: 10.1016/S0140-6736(17)32400-5. Epub 2017 Sep 15. Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre international randomised controlled trial. Abstract.

Editor's Note: This article was updated after publication to include Dr Hammond's comments.

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