Intrapartum and Early Postpartum Use of Automated Insulin Delivery in Type 1 Diabetes: A Prespecified Analysis of the CIRCUIT Randomized Controlled Trial

OBJECTIVE: Following the demonstrated improvement in pregnancy glycemia with Control-IQ closed loop in the Closed loop Insulin delivery by glucose Responsive Computer algorithms In Type 1 diabetes pregnancies (CIRCUIT) trial, we compared intrapartum and early postpartum glycemic effectiveness and safety with standard care in type 1 diabetes. RESEARCH DESIGN AND METHODS: The primary outcome of this prespecified analysis was percentage of time in pregnancy-specific glucose range (63-140 mg/dL) during the 24 h prior to childbirth, measured by continuous glucose monitoring. A key secondary outcome was percentage of time at <70 mg/dL in the first postpartum week, with additional secondary outcomes including continuous glucose monitoring metrics through 6 weeks postpartum. Analyses were adjusted for baseline measure, insulin delivery mode, and site. RESULTS: In the intrapartum period (24 h before delivery), 39 of 44 (89%) participants continued closed loop. Intravenous insulin was used intrapartum by one (2%) closed loop participant and 20 (45%) standard care participants (P < 0.001). Intrapartum closed loop users spent more time in pregnancy-specific glucose range (79.6% vs. 64.8%) than the standard-care group (mean adjusted difference 13.2 percentage points; 95% CI 5.2, 21.2). In the first postpartum week, the closed loop group spent less time <70 mg/dL (1.7% vs. 3.2%; mean adjusted difference -1.8 percentage points; 95% CI -0.9 to -2.7) compared with the standard care group. No maternal severe hypoglycemia occurred in the closed loop group, while one episode occurred in the standard care group postpartum. No diabetic ketoacidosis occurred in either group. CONCLUSIONS: Use of this closed loop system resulted in superior intrapartum and early postpartum glycemia compared with standard care, without safety concerns. Together with previous results, this supports use of this closed loop system throughout pregnancy, labor, and the early postpartum period.