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.