Advanced Hybrid Closed Loop Systems in Pregnancy: A Retrospective Study of Women With Type 1 Diabetes

Hybrid closed loop systems (HCLS) lead to improved glycaemic outcomes without the increased burden of hypoglycemia. CamAPS and Mendtronic 780G are the only systems licensed for use in pregnancy in Europe; however, all the commercially available algorithms are currently used in clinical practice. The aim of this study is to share our experience of using HCLS during pregnancy.

This is a retrospective study. We reviewed records at two teaching hospitals from January 2018-March 2023 and identified 42 women of whom 42.8% (n = 18) were established on HCLS prior to pregnancy and 57.2% (n = 24) started during pregnancy at a median of 12 weeks of gestation.

Time in pregnancy target range (TIRp) (3.5-7.8 mmol/L) increased from 57% (44.5%-65%) (median, IQR) at first visit to 73% (65%-82%) (p < 0.001) at 34 weeks of gestation with 66% achieving ≥ 70% at 34 weeks. Time below range (TBR) glucose did not change significantly. There was no significant difference in TIRp at 8 or 34 weeks between those started on HCLS before versus during pregnancy. TBR at first visit was lower in those established on HCLS pre-pregnancy versus those started in pregnancy (p: 0.04) with no difference between groups at 34 weeks. There were no admissions for diabetic ketoacidosis (DKA) or severe hypoglycemia. Eleven infants (26.8%) had birthweight over 90th percentile and neonatal hypoglycemia was recorded in 9 cases (22%).

In our cohort, HCLS in pregnancy was effective, with 66% achieving ≥ 70% TIRp, and appears to be safe with low TBR and no episodes of DKA.