Issue: November 2023
Fact checked byRichard Smith

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October 09, 2023
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Hybrid closed-loop therapy increases time in range for pregnant women with type 1 diabetes

Issue: November 2023
Fact checked byRichard Smith
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Key takeaways:

  • Pregnant women with type 1 diabetes had a higher time in range with use of a hybrid closed-loop insulin delivery system vs. standard care.
  • Hypertensive disorders were less common with hybrid closed-loop therapy.

Hybrid closed-loop insulin delivery can increase time in range for pregnant women with type 1 diabetes with no safety concerns, according to trial findings presented at the European Association for the Study of Diabetes annual meeting.

In the AiDAPT trial, pregnant women with type 1 diabetes were randomly assigned to a hybrid closed-loop insulin delivery system or standard care from 16 weeks gestation until delivery. In data that were simultaneously published in The New England Journal of Medicine, the hybrid closed-loop group had a time in range 10.5 percentage points higher than the standard care group, with no differences observed in most neonatal and fetal outcomes.

Hybrid closed-loop therapy improves time in range for pregnant women with type 1 diabetes.
Data were derived from Murphy H. Oral presentation 39. Presented at: European Association for the Study of Diabetes Annual Meeting; Oct. 2-6, 2023; Hamburg, Germany (hybrid meeting).

“We would recommend that hybrid closed-loop, from here on in, should be offered to all pregnant women with type 1 diabetes, definitely during pregnancy and ideally starting prepregnancy,” Helen R. Murphy, MD, professor of medicine in diabetes and antenatal care at the University of East Anglia and honorary consultant physician at Norfolk & Norwich University Hospital NHS Trust in the U.K., said during a presentation.

Researchers conducted an open-label randomized controlled trial with 124 pregnant women aged 18 to 45 years with type 1 diabetes who were receiving intensive insulin therapy and had an HbA1c between 6.5% and 10% at baseline (mean age, 31.1 years; mean HbA1c, 7.7%). Women participated in a 96-hour continuous glucose monitoring run-in period before randomization to collect baseline data. After recruitment and before 16 weeks gestation, participants were randomly assigned to an intervention arm in which they used a hybrid closed-loop system consisting of a smartphone with the CamAPS FX app (CamDiab), the Dana Diabecare RS insulin pump (Sooil) and the Dexcom G6 CGM (n = 61) or a standard care group that continued multiple daily insulin injections or insulin pump therapy with dose adjustments directed by their care team (n = 63). All participants attended in-person or virtual study visits every 4 weeks. CGM data were collected at each visit, blood samples were taken at weeks 24 to 26 and weeks 34 to 36 gestation and follow-up questionnaires were conducted at weeks 34 to 36. The primary outcome was the time in range between 63 mg/dL and 140 mg/dL from 16 weeks gestation until delivery.

Hybrid closed-loop therapy improves time in range

Women in the standard care group had more additional clinic visits and more unscheduled contacts with providers than the hybrid closed-loop group. CGM was used 97% of the time in both groups and women in the intervention group used the closed-loop system 96% of the time.

Women in the hybrid closed-loop group had an increase in time in range from 47.8% at baseline to 68.2% during the trial. Time in range increased in the standard care group from 44.5% at baseline to 55.6% during the trial. The hybrid closed-loop group had a greater increase in time in range compared with standard care (adjusted mean difference, 10.5 percentage points; 95% CI, 7-14; P < .001). The change in time in range did not differ by age, baseline HbA1c or pre-enrollment insulin therapy.

“The time of day that the difference between the intervention and the control is most marked is, as excepted, during the overnight time, with women consistently reaching 90% time in range [with hybrid closed-loop therapy] during overnight,” Murphy said.

Time above range with a glucose level more than 140 mg/dL (29% vs. 41%; P < .001) and more than 180 mg/dL (11% vs. 17%; P < .001) was lower in the intervention group compared with standard care. No difference was observed for time below range.

A lower proportion of women in the hybrid closed-loop group had hypertensive disorders compared with standard care (20% vs. 42%; P = .02). The intervention group had a mean maternal weight gain of 11.1 kg compared with a 14.1 kg weight gain with standard care (P = .02).

There were no differences in birth weight, and fetal and neonatal outcomes were similar between the two groups. However, Murphy noted there was difference in gestational age at delivery.

“We saw, for reasons that are not entirely clear, a slightly earlier gestation of delivery in the intervention arm, with babies being delivered on average 4.5 days earlier,” Murphy said.

More research on therapy initiation, target glucose needed

In a related commentary published in The New England Journal of Medicine, Satish K. Garg, MD, professor of medicine and pediatrics at the Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical Campus, and Sarit Polsky, MD, MPH, assistant professor of medicine and pediatrics at the Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical Campus, wrote that the trial revealed how a hybrid closed-loop system can be “safe and effective when customizable glucose targets within the pregnancy-specific target glucose range are used.” However, they said several questions were unanswered in the trial, including when hybrid closed-loop therapy should be initiated.

Satish K. Garg

“Participants underwent randomization at approximately 11 weeks gestation, which missed the crucial period of organogenesis,” Garg and Polsky wrote. “Evidence suggests that a higher percentage of time in the target glucose range in the first 10 weeks of gestation reduces the risk of infants being born large for their gestational age, which raises the question of whether earlier closed-loop initiation could further affect neonatal health. Participants who were randomly assigned to the closed-loop group during the first trimester of pregnancy did have a higher percentage of time in the target glucose range by 12 weeks gestation than those in the standard-care group, which suggests that even earlier closed-loop use may be beneficial.”

Garg and Polsky added that the trial did not examine whether hybrid closed-loop therapy may benefit women with an HbA1c of less than 6.5%, whether a closed-loop system should use a pregnancy-specific target range or algorithm to determine glycemic target, whether early initiation can help women avoid adverse maternal and neonatal outcomes, and whether hybrid closed-loop therapy may confer benefits for women with type 2 diabetes or gestational diabetes.

“Clearly, closed-loop systems have changed the landscape of diabetes care in nonpregnant populations,” Garg and Polsky wrote. “Although more studies are needed, the AiDAPT trial provides hope that this landscape may also be altered for the better for pregnant persons with type 1 diabetes.”

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