Closed-Loop Insulin Delivery in Type 1 Diabetes in Pregnancy
Lois Donovan, Patricia Lemieux, Amy D. Dunlop, Jennifer M. Yamamoto, Helen R. Murphy, David Simmons, Rhonda C. Bell, Kathleen H. Chaput, Jamie L. Benham, Glynis P. Ross, Kara Nerenberg, Jane E. Booth, Bruce A. Perkins, Khorshid Mohammad, Henry Ntanda, James A. King, George Tomlinson, Denice S. Feig, CIRCUIT Collaborative Group, Julie McKeen, Amita Mahajan, Hanan Bassyouni, Bianca Cot, Afshan Zahedi, Geetha Mukerji, Ariane Godbout, Ilana Halperin, Jason Kong, Selina Liu, Ruth McManus, Tamara Spaic, Jillian Coolen, Thomas Ransom, N. Wah Cheung, Jina Rhou, Suja Padmanabhan, Arianne Sweeting, Christopher J. Nolan, Sarah Price, Alison Namkervis
Abstract
Importance: Hyperglycemia-related pregnancy complications occur in 50% of pregnant women with type 1 diabetes. Closed-loop insulin systems improve glycemia outside of pregnancy but have had limited testing in pregnancy. Objective: To assess the efficacy of a closed-loop system in pregnancy. Design, Setting, and Participants: Open-label trial enrolling pregnant women with type 1 diabetes at 14 clinical centers in Canada and Australia before 14 weeks' gestation with follow-up until 6 weeks postpartum. Enrollment occurred between June 2021 and July 2024 and follow-up was completed in March 2025. Interventions: Participants were randomized 1:1 to closed-loop therapy (n = 46) or standard care (insulin pump or multiple daily insulin injections) (n = 45) with continuous glucose monitoring. Main Outcomes and Measures: The primary outcome was the percentage of time spent in the pregnancy-specific glucose range (63-140 mg/dL), measured by continuous glucose monitoring from 16 to 34 weeks' gestation. Results: Among 94 enrolled participants, 3 experienced pregnancy loss prior to randomization, 91 were randomized (mean age, 31.7 [SD, 5.2] years; early pregnancy hemoglobin A1c, 7.4% [SD, 1.0%]), and 88 were included in the primary analysis. The mean percentage of time spent in the pregnancy-specific glucose range from 16 to 34 weeks' gestation was 65.4% in the closed-loop group and 50.3% in the standard care group (mean adjusted difference, 12.5 [95% CI, 9.5-15.6] percentage points; P < .001). There was 1 episode of severe hypoglycemia in the closed-loop group, and there were 2 episodes of diabetic ketoacidosis in the closed-loop group and 1 in the standard care group. Conclusion and Relevance: Pregnant women with type 1 diabetes using a closed-loop system spent significantly more time in the pregnancy-specific glucose range than those receiving standard care. These findings support the use of this closed-loop system in pregnant women with type 1 diabetes. Trial Registration: ClinicalTrials.gov Identifier: NCT04902378.