News Release

Automated insulin delivery in women with pregnancy complicated by Type 1 diabetes

The New England Journal of Medicine: Hybrid closed-loop technology improved maternal glucose levels during pregnancy complicated by type 1 diabetes

Peer-Reviewed Publication

University of Leeds

Automated Insulin Delivery in Women with Pregnancy Complicated by Type 1 Diabetes

The New England Journal of Medicine: Hybrid Closed-Loop technology improved maternal glucose levels during pregnancy complicated by type 1 diabetes.

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

For pregnant women with type 1 diabetes, a technology giving insulin doses as informed by a smartphone algorithm, helps them better manage their blood sugars, compared to traditional insulin pumps or multiple daily injections, according to a new randomised trial published in The New England Journal of Medicine and presented at the European Association for the Study of Diabetes (EASD) meeting.

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.

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.

In the study, researchers trialled a technology known as Hybrid Closed-Loop or Artificial Pancreas. The technology consists of an algorithm which sits on a smartphone and communicates with the traditional continuous glucose monitoring and insulin pump systems. The system adjusts insulin doses every 10-12 minutes according to blood sugar levels, meaning that it continuously responds to the persistent changes in blood sugar levels throughout pregnancy. 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.

Eleanor Scott, Professor of Medicine (Diabetes and Maternal Health) in the University of Leeds' School of Medicine, said: "This is the good news that pregnant women with type 1 diabetes and NHS maternity services have been waiting for. It is great to see advances in diabetes technology come to fruition and deliver such improvements for pregnancy. Having recently successfully implemented continuous glucose monitoring uniformly across the NHS in England to improve mother and baby outcomes for pregnant women with Type 1 diabetes, we are now well positioned for a similar roll out of hybrid closed loop to improve the situation further

The study involved 124 pregnant women with type 1 diabetes aged 18-45 years who managed their condition with daily insulin therapy. Half were randomly allocated to use the Hybrid Closed-Loop technology, and half to use the traditional insulin therapy (insulin pumps or multiple daily injection methods). They took part for approximately 24 weeks (from 10-12 weeks) until the end of pregnancy. The study took place in 9 NHS hospitals in England, Scotland, and Northern Ireland.


On average, pregnant women used the Hybrid Closed-Loop technology for more 95% of the time. 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 2.5-3.0 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 across of all ages, and regardless of their previous blood sugar levels or previous insulin therapy.  These improvements were achieved without additional low blood glucose events, 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.


“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,” says lead author Professor Helen Murphy (University of East Anglia, Norwich, UK). “We know that 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.  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 is game changing, in that it will allow more women to have safer, healthier, more enjoyable pregnancies, with potential for lifelong benefits for their babies.” [1]


The researchers note some limitations, including that the current study was too small for a detailed examination of baby health outcomes, and that their results are specific to the CamAPS technology, so cannot be extrapolated to closed-loop systems, with higher blood sugar targets, that may not be applicable for use during pregnancy.


The study was funded by the Efficacy and Mechanism Evaluation (EME) Program, an MRC and NIHR partnership and supported by the Juvenile Diabetes Research Foundation (JDRF), and the Diabetes Research & Wellness Foundation (DRWF). The views expressed in this publication are those of the authors and not necessarily those of the Medical Research Council (MRC), National Institute for Health and Care Research (NIHR), or the Department of Health and Social Care. A full declaration of interests is included in the article. The study was conducted by researchers from the Norfolk and Norwich University Hospitals NHS Foundation Trust and University of East Anglia, Norwich, Cambridge University Hospitals NHS Foundation Trust, and the Wellcome-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, the Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, the Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, King’s College Hospital NHS Foundation Trust, London, the Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Belfast, Barnard Health Research, Southampton, and the Usher Institute and the Centre for Cardiovascular Science, University of Edinburgh, Edinburgh — all in the UK; and the Jaeb Center for Health Research, Tampa, Florida, USA.

[1] Quote direct from author and cannot be found in the text of the Article.

For interviews with the Article authors Prof Helen Murphy, University of East Anglia, Norwich, UK please contact: Email: or Tel: 0044 7595 166852

Prof Roman Hovorka, University of Cambridge, Cambridge, UK please contact Email: or Tel 7776 252445

Prof Eleanor Scott, University of Leeds, Leeds, UK please contact Email: or Tel: 0044 7876 031952

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