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New trial shows benefits of hybrid closed loop in pregnancy  

A JDRF-supported trial published in the New England Journal of Medicine and presented at the European Association for the Study of Diabetes conference has shown that hybrid closed loop technology helps pregnant women better manage their blood sugars compared to traditional insulin pumps or multiple daily injections.  
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Kate Gerrard 5 October 2023

A woman with type 1 diabetes who is discussing pregnancy with a nurse

Authors say that hybrid closed-loop technology should now be offered to all pregnant women with type 1 diabetes.

How does type 1 affect pregnancy?

Despite better systems for monitoring blood sugars and delivering insulin, altered eating behaviours and hormonal changes during pregnancy mean that most women struggle to reach the recommended blood sugar targets. This means that complications related to having type 1 diabetes during pregnancy are widespread, affecting one in every two newborn babies.

For the baby, these include premature birth, need for intensive care after birth, and being too large at birth, which increases the lifelong risk of overweight and obesity. Low blood sugars, excess weight gain, and high blood pressure during pregnancy are common amongst mothers.

What did the study look at?

In the study, researchers trialled hybrid closed loop, also known as the artificial pancreas. They compared this technology with the traditional continuous glucose monitoring and insulin systems, where women supported by specialist diabetes maternity teams make multiple daily decisions about insulin doses.

The study involved 124 pregnant women with type 1 diabetes aged 18-45 years who managed their condition with daily insulin therapy. They took part for approximately 24 weeks (from 10-12 weeks until the end of pregnancy). The study took place in nine NHS hospitals in England, Scotland, and Northern Ireland.

What did the study show us?

Using the technology helped to substantially reduce maternal blood sugars throughout pregnancy.

Compared to traditional insulin therapy methods, women who used the technology spent more time in the target range for pregnancy blood sugar levels (68% vs 56% – equivalent to an additional 2.5-3 hours every day throughout pregnancy).

It was safely initiated during the first trimester, which is a crucially important time for babies’ development. The blood sugar levels improved consistently in mothers of all ages, and regardless of their previous blood sugar levels or previous insulin therapy.

These improvements were achieved without additional hypos and without additional insulin. Women using the technology also gained 3.5 kg (equal to 7.7 lbs) less weight and were less likely to have blood pressure complications during pregnancy.

Importantly, women using the technology also had fewer antenatal clinic appointments, and fewer out-of-hours calls with maternity clinic teams, suggesting that this technology could also be time-saving for pregnant women and for stretched maternity services.

The authors of the study say that, as a result of these findings, this type of technology should now be offered to all pregnant women with type 1 diabetes to help improve maternal blood sugars.

What do the researchers say?

Lead author, Professor Helen Murphy of the University of East Anglia says: “For a long time, there has been limited progress in improving blood sugars for women with type 1 diabetes, so we’re really excited that our study offers a new option to help pregnant women manage their diabetes.

“Previous studies have confirmed that every extra hour spent in the blood sugar target range reduces the risks of premature birth, being too large at birth and need for admission to neonatal intensive care unit. This technology will allow more women to have safer, healthier, more enjoyable pregnancies, with potential for lifelong benefits for their babies.

“JDRF’s support has been immense. It has allowed us to work with the Jaeb Center for Health Research, who are world leaders in diabetes technology research. They worked alongside our local Norwich Clinical Trials Unit to ensure that our research and the analysis of vast amounts of GCM data was performed to the highest standards.”

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