Who Benefits Most from Advanced Hybrid Closed Loop Therapy in Pregnancy Across Different Subgroups: A Secondary Analysis of the Randomized Controlled CRISTAL Trial.

Objective: The CRISTAL trial indicated that advanced hybrid closed loop (AHCL) therapy with MiniMed™ 780G in type 1 diabetes pregnancy did not improve time in range (TIRp) compared with standard insulin therapy (SoC), but improved TIRp overnight and reduced time below range (TBRp). We aimed to evaluate the effect of AHCL therapy across different subgroups. Research Design and Methods: This secondary analysis of the CRISTAL randomized controlled trial compared glycemic outcomes (TIRp, TIRp overnight, TBRp, and TBRp overnight) averaged over the antenatal period (14-, 20-, 26-, and 33-weeks' gestation) between the AHCL and SoC groups, within subgroups defined by baseline characteristics. Results: In women with baseline HbA1c <7.0%, the AHCL group (n = 35) had a significantly higher TIRp than SoC (n = 37), with a mean difference of 5.64% (95% confidence interval [95% CI]: 1.32-9.96), corresponding to 1 h 21 min more TIRp per day and 11.89% (95% CI: 7.01-16.76) higher TIRp overnight. In women without prior AHCL use, TIRp was 6.29% higher (95% CI: 0.90-11.68) and overnight TIRp 11.91% higher (95% CI: 5.65-18.16) in the AHCL group (n = 24) compared with SoC (n = 28). In women without higher education, AHCL users (n = 14) had a significantly higher TIRp compared with SoC (n = 14) with a difference of 7.33% (95% CI: 0.88-13.78). TBRp was significantly lower in AHCL users with baseline HbA1c <7.0% and in women without prior AHCL use. Conclusions: AHCL therapy improved glycemic management in pregnant women with baseline HbA1c <7.0%, in women without prior AHCL use, and in women without higher education, indicating that AHCL might particularly benefit these subgroups.