Closed-loop insulin delivery in type 1 diabetes in pregnancy: the CIRCUIT randomized clinical trial

Lois E. 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 A. Nerenberg; Jane E. Booth; Bruce A. Perkins; Khorshid Mohammad; Henry N. Ntanda; James A. King; George Tomlinson; Denice S. Feig

doi:10.1001/jama.2025.19578

Closed-loop insulin delivery in type 1 diabetes in pregnancy: the CIRCUIT randomized clinical trial

Lois E. 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 A. Nerenberg
, Jane E. Booth
, Bruce A. Perkins
, Khorshid Mohammad
, Henry N. Ntanda
, James A. King
, George Tomlinson
, Denice S. Feig

School of Medicine

University of Calgary
Université Laval
University of Manitoba
University of East Anglia
Ingham Institute
Campbelltown Hospital
University of Alberta
University of Sydney
University of Toronto
Alberta Health Services
Alberta SPOR SUPPORT Unit
Toronto General Hospital Research Institute

Research output: Contribution to journal › Article › peer-review

5 Citations (Scopus)

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 A_1c, 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.

Original language	English
Pages (from-to)	2176-2185
Number of pages	10
Journal	JAMA
Volume	334
Issue number	24
DOIs	https://doi.org/10.1001/jama.2025.19578
Publication status	Published - 23 Dec 2025

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SDG 3 Good Health and Well-being

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10.1001/jama.2025.19578

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Donovan, L. E., Lemieux, P., Dunlop, A. D., Yamamoto, J. M., Murphy, H. R., Simmons, D., Bell, R. C., Chaput, K. H., Benham, J. L., Ross, G. P., Nerenberg, K. A., Booth, J. E., Perkins, B. A., Mohammad, K., Ntanda, H. N., King, J. A., Tomlinson, G., & Feig, D. S. (2025). Closed-loop insulin delivery in type 1 diabetes in pregnancy: the CIRCUIT randomized clinical trial. JAMA, 334(24), 2176-2185. https://doi.org/10.1001/jama.2025.19578

@article{6b0b51308bbe477598750458c57effde,

title = "Closed-loop insulin delivery in type 1 diabetes in pregnancy: the CIRCUIT randomized clinical trial",

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{\textquoteright} 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{\textquoteright} 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{\textquoteright} 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. ",

author = "Donovan, \{Lois E.\} and Patricia Lemieux and Dunlop, \{Amy D.\} and Yamamoto, \{Jennifer M.\} and Murphy, \{Helen R.\} and David Simmons and Bell, \{Rhonda C.\} and Chaput, \{Kathleen H.\} and Benham, \{Jamie L.\} and Ross, \{Glynis P.\} and Nerenberg, \{Kara A.\} and Booth, \{Jane E.\} and Perkins, \{Bruce A.\} and Khorshid Mohammad and Ntanda, \{Henry N.\} and King, \{James A.\} and George Tomlinson and Feig, \{Denice S.\}",

year = "2025",

month = dec,

day = "23",

doi = "10.1001/jama.2025.19578",

language = "English",

volume = "334",

pages = "2176--2185",

journal = "JAMA",

issn = "0098-7484",

publisher = "American Medical Association",

number = "24",

}

Donovan, LE, Lemieux, P, Dunlop, AD, Yamamoto, JM, Murphy, HR, Simmons, D, Bell, RC, Chaput, KH, Benham, JL, Ross, GP, Nerenberg, KA, Booth, JE, Perkins, BA, Mohammad, K, Ntanda, HN, King, JA, Tomlinson, G & Feig, DS 2025, 'Closed-loop insulin delivery in type 1 diabetes in pregnancy: the CIRCUIT randomized clinical trial', JAMA, vol. 334, no. 24, pp. 2176-2185. https://doi.org/10.1001/jama.2025.19578

TY - JOUR

T1 - Closed-loop insulin delivery in type 1 diabetes in pregnancy

T2 - the CIRCUIT randomized clinical trial

AU - Donovan, Lois E.

AU - Lemieux, Patricia

AU - Dunlop, Amy D.

AU - Yamamoto, Jennifer M.

AU - Murphy, Helen R.

AU - Simmons, David

AU - Bell, Rhonda C.

AU - Chaput, Kathleen H.

AU - Benham, Jamie L.

AU - Ross, Glynis P.

AU - Nerenberg, Kara A.

AU - Booth, Jane E.

AU - Perkins, Bruce A.

AU - Mohammad, Khorshid

AU - Ntanda, Henry N.

AU - King, James A.

AU - Tomlinson, George

AU - Feig, Denice S.

PY - 2025/12/23

Y1 - 2025/12/23

N2 - 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.

AB - 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.

UR - https://www.scopus.com/pages/publications/105022102341

UR - https://go.openathens.net/redirector/westernsydney.edu.au?url=https://doi.org/10.1001/jama.2025.19578

U2 - 10.1001/jama.2025.19578

DO - 10.1001/jama.2025.19578

M3 - Article

C2 - 41134589

AN - SCOPUS:105022102341

SN - 0098-7484

VL - 334

SP - 2176

EP - 2185

JO - JAMA

JF - JAMA

IS - 24

ER -

Closed-loop insulin delivery in type 1 diabetes in pregnancy: the CIRCUIT randomized clinical trial

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