Advanced Hybrid Closed-Loop Therapy Compared With Standard Insulin Therapy Intrapartum and Early Postpartum in Women With Type 1 Diabetes: A Secondary Observational Analysis From the CRISTAL Randomized Controlled Trial

OBJECTIVE To determine efficacy and safety of intrapartum and early postpartum advanced hybrid closed-loop (AHCL) therapy compared with standard insulin therapy in pregnant women with type 1 diabetes (T1D). RESEARCH DESIGN AND METHODS CRISTAL was a double-arm, open-label, randomized controlled trial performed in Belgium and the Netherlands that assigned 95 pregnant participants with T1D 1:1 to a MiniMed 780G AHCL system (n = 46) or standard insulin therapy (n = 49). This prespecified, secondary observational analysis focused on differences in glycemic control and safety outcomes between participants from the original AHCL group who continued AHCL intrapartum (n = 27) and/or early postpartum (n = 37, until hospital discharge) and those from the original standard insulin therapy group using standard insulin therapy intrapartum (n = 45) and/or early postpartum (n = 34). RESULTS Of the 43 and 46 participants in the AHCL and standard insulin therapy groups, respectively, completing the trial, 27 (62.8%) in the AHCL group continued AHCL and 45 in the standard insulin therapy group (97.8%) continued standard insulin therapy intrapartum. Compared with standard insulin therapy, intrapartum AHCL was associated with more time in range 3.5–7.8 mmol/L (71.5 ± 17.7% vs. 63.1 ± 17.0%, P = 0.030) and numerically lower time above range 7.8 mmol/L (27.3 ± 17.4% vs. 35.3 ± 17.5%, P = 0.054), without increases in time below range 3.5 mmol/L (1.1 ± 2.4% vs. 1.5 ± 2.3%, P = 0.146). Early postpartum, 37 (86.0%) participants randomized to AHCL continued AHCL, with a median increase in insulin-to-carbohydrate ratios of 67% (interquartile range −14 to 126). Similar tight glycemic control (3.9–10.0 mmol/L: 86.8 ± 6.7% vs. 83.8 ± 8.1%, P = 0.124) was observed with AHCL versus standard insulin therapy. No severe hypoglycemia or diabetic ketoacidosis was reported in either group. CONCLUSIONS AHCL is effective in maintaining tight glycemic control intrapartum and early postpartum and can be safely continued during periods of rapidly changing insulin requirements.