Study rationale, method, and findings
Pregnant women with diabetes are advised to aim for very tight glucose targets throughout pregnancy and avoid hyperglycemia, to reduce risk of preterm delivery, neonatal weight > 90th percentile, and neonatal morbidity, according to Dr. Murphy and colleagues.
“However, despite increased use of [CGM], continuous subcutaneous insulin infusion (CSII), and improved insulin analogs, achieving and maintaining the recommended glucose targets remains challenging for most pregnant women with type 1 diabetes,” they wrote in their abstract.
Researchers randomized 124 women who had type 1 diabetes for at least 12 months, were at < 13 weeks’ to 6 days’ gestation, and had an A1c of 6.5% to < 10% who were taking intensive standard insulin therapy at nine antenatal clinics in the United Kingdom. Half of the women were using CSII and half were receiving multiple daily injections of insulin.
As explained in the published study protocol, the women were randomized to continue their standard insulin delivery or switch to a closed-loop system consisting of the study insulin pump (Dana Diabecare RS), a CGM transmitter, and an app (CamAPS FX) on an Android smartphone that communicates wirelessly with the insulin pump and CGM transmitter.
Participants in both groups used the same CGM system and received support for insulin dose adjustment from their antenatal clinical care team.
They were a mean age of 31 years, had a mean A1c of 7.7%, and had had type 1 diabetes for 17 years on average. Their body mass index varied; 37% had normal weight, 27% had overweight, and 26% had obesity.
A significantly higher percentage of women in the AID group than in the control group had blood glucose in target range more than 70% of the time (46% vs. 10%; P < .001).
Compared with women in the control group, those in the AID group had larger reductions in hyperglycemia (–11%; P < .001), higher overnight time-in-range (13%; P < .001), and lower A1c (–0.34%; P < .001), without additional insulin, weight gain, or hypoglycemia.
The effect was consistent across clinical sites and maternal age and A1c categories.
Ongoing studies, off-label use
Hybrid closed-loop systems “including Tandem Control IQ, the Omnipod 5, and the Medtronic 780G give insulin continuously on the basis of values obtained from a sensor,” Dr. Peters explained in a recent commentary. “These aren’t fully closed-loop systems because the individual still has to interact with the system and give doses for meals, and then adjust doses for exercise.”
There are currently three studies using commercially available AID systems without pregnancy-specific glucose targets, in type 1 diabetes pregnancies, Dr. Polsky noted.
The Pregnancy Intervention With a Closed-Loop System (PICLS) trial used the Medtronic 670G system in pregnancy and was conducted in the United States. The Closed-Loop Insulin Delivery in Pregnant Women With Type 1 Diabetes (CRISTAL) study is using the Medtronic 780G system in pregnancy and is being conducted in Belgium and the Netherlands. And the Closed-Loop Insulin Delivery in Type 1 Diabetes Pregnancies (CIRCUIT) study is using the Tandem Control IQ system in pregnancy and is being conducted in Canada, she explained.
“The decision to continue to use or to initiate (off-label) use of any of these systems in pregnancy should be individualized, and pregnant individuals should make these decisions by working with an experienced endocrine/diabetes team,” Dr. Polsky stressed.
“The hope is that the results of these exciting trials will show safe and effective use of these systems throughout gestation with improvements in glucose control and quality of life,” she concluded.
The study was funded by the UK National Institute for Health Research, JDRF, and Diabetes Research and Wellness Foundation. Dr. Murphy has reported being on the advisory panel for Medtronic and receiving research support from Dexcom. Dr. Peters disclosed that she served as a consultant for Blue Circle Health, Vertex, and Abbott Diabetes Care, received a research grant from Abbott Diabetes Care, and received stock options from Teladoc and Omada Health. Dr. Polsky has disclosed that she is a contributing writer for diaTribe, was on a medical advisory board for Medtronic MiniMed, has received research funding from DexCom, Eli Lilly, JDRF, Leona & Harry Helmsley Charitable Trust, NIDDK, and Sanofi, and has received research support from Diasome Pharmaceuticals, LabStyle Innovation, Lexicon, Medtronic MiniMed, and Sanofi.
A version of this article first appeared on Medscape.com.