Changes to insulin pump settings throughout pregnancy for individuals using assisted hybrid closed-loop therapy...

We compared changes in insulin pump settings and insulin distribution throughout pregnancy and early postpartum for participants with type 1 diabetes using sensor-augmented pump therapy (SAPT) or hybrid closed-loop (HCL) therapy without a pregnancy-specific glucose target.

In this investigator-initiated trial 23 participants were randomized at 14-18 weeks gestation to HCL therapy or SAPT until 4-6 weeks postpartum. We compared the changes to insulin pump settings and insulin delivery between groups using mixed-effects models.

There were no significant differences in total daily insulin dose between HCL and SAPT groups from preconception through 4-6 weeks postpartum. However, the proportion of total insulin coming from bolus insulin was higher for the HCL group in month 9 (70.9 % HCL vs 57.9 % SAPT, p = 0.014). The HCL group had a lower total daily basal dose compared to SAPT in months 9 and 10 (p < 0.05 for both) and a higher total daily bolus dose at month 10 compared to the SAPT group (55.2 units/day vs 37.1 units/day, p = 0.025). The number of changes to pump settings did not differ between groups. Active insulin time was significantly shorter in the HCL group at almost all time points through month 9 of pregnancy and early postpartum. Carbohydrate-to-insulin ratios were stronger for breakfast (p = 0.020) and lunch (p = 0.005) over gestation in the HCL group.

More bolus insulin and less basal insulin were used by the HCL group compared to the SAPT group, at least in part due to pump settings that contribute to more bolus insulin delivery.