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Automated Insulin Delivery Improves Maternal Glucose Control for Women with Type 1 Diabetes

Experts urged that hybrid closed-loop technology be offered to all pregnant women with type 1 diabetes as research showed it improved maternal glucose levels during pregnancy complicated by type 1 diabetes.

Despite better systems for monitoring blood glucose and delivering insulin, hormonal changes and altered eating patterns during pregnancy meant that "most women struggle to reach the recommended blood sugar targets", said the authors of a UK study published in the New England Journal of Medicine

This meant that complications related to the condition during pregnancy were "widespread", affecting one in every two newborn babies, they said.

Lead author Professor Helen Murphy from the University of East Anglia said there had been "limited progress" in improving blood glucose levels for women with type 1 diabetes in pregnancy. "For women with type 1 diabetes, unborn babies are exquisitely sensitive to small rises in blood sugars, so keeping blood sugar levels within the normal range during pregnancy is crucial to reduce risks for the mother and child," she explained.

Previous studies had confirmed that "every extra hour" spent in the blood sugar target range reduced the risks of premature birth, being too large at birth, and need for admission to neonatal intensive care unit, she underlined.

Promising New Technology 

The efficacy of hybrid closed-loop insulin therapy in managing type 1 diabetes during pregnancy had remained "unclear", the authors emphasised.

For their investigation, presented at the annual meeting of the European Association for the Study of Diabetes this week, researchers compared a hybrid closed-loop system with current continuous glucose monitoring and insulin systems.

The multicentre controlled trial at nine UK hospital sites involved 124 pregnant women with type 1 diabetes, with a mean age of 31.1 years, who managed their condition with daily insulin therapy. The women were randomly assigned to use the hybrid closed-loop technology, or traditional insulin therapy, with both groups using continuous glucose monitoring. 

The participants took part for approximately 24 weeks, from 10 to 12 weeks until the end of pregnancy. Primary outcome was percentage of time in the pregnancy-specific target glucose range — 63 to 140 mg per decilitre [3.5 to 7.8 mmol per litre] — measured by continuous glucose monitoring from 16 weeks' gestation until delivery. Key secondary outcomes were the percentage of time spent in a hyperglycaemic state, overnight time in the target range, glycated haemoglobin level, and safety events.

Additional Health Benefits Expected

"Using the technology helped to substantially reduce maternal blood sugars throughout pregnancy," the researchers reported. 

Compared with traditional insulin therapy methods, women who used the technology spent more time in the target range for pregnancy blood glucose levels (68.2% vs 55.6%), which equated to an additional 2.5 to 3.0 hours every day throughout pregnancy.

Previous studies showed that every increase of 5 percentage points of time in the target range was associated with improved obstetrical and neonatal outcomes, highlighted the authors. Study participants gained an additional 10 percentage points of time in the target range above the 10 percentage-point increment seen with continuous glucose monitoring and standard insulin therapy during pregnancy. 

Although the trial was not powered for pregnancy outcomes, the authors inferred that this would be "expected to have additional health benefits" for pregnant women and their babies.

Women using the technology also gained 3.5 kg 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," highlighted the authors, which meant the technology could be "time saving for pregnant women and for stretched maternity services".

Participants in the closed-loop group spent less time in a hyperglycaemic state than those in the standard-care group, had more overnight time in the target, and had lower glycated haemoglobin levels. No unanticipated safety problems associated with the use of closed-loop therapy during pregnancy occurred, reassured the authors.

Game-Changing Option

"For pregnant women with type 1 diabetes, this type of technology should now be offered," they suggested. Professor Murphy hailed the technology as "game changing" and highlighted that it would allow more women to have "safer, healthier, more enjoyable pregnancies, with potential for lifelong benefits for their babies".

In a linked editorial, Satish K. Garg, MD, and Sarit Polsky, MD from the Barbara Davis Center for Diabetes at the University of Colorado, commented, "Clearly, closed-loop systems have changed the landscape of diabetes care in nonpregnant populations. Although more studies are needed, the trial provides hope that this landscape may also be altered for the better for pregnant persons with type 1 diabetes."

Commenting to Medscape News UK, Dr Faye Riley, research communications manager at Diabetes UK, emphasised the importance of the study in demonstrating how hybrid closed loop technology could help "transform management of type 1 during pregnancy, offering safer blood sugar management, reducing the amount of time needed with healthcare professionals, and making for healthier mums and babies". 

She pointed out that draft National Institute for Health and Care Excellence recommendations for hybrid closed loop technology "rightly acknowledge" the technology's benefits for pregnant women with type 1 diabetes, "prioritising them for access".

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