Real-world evidence of off-label use of commercially automated insulin delivery systems compared to multiple daily insulin injections in pregnancies complicated by type 1 diabetes.

To compare glycemic control and maternal-fetal outcomes of women with type 1 diabetes (T1D) using hybrid closed loop (HCL) vs. multiple daily insulin injections (MDI) plus continuous glucose monitoring (CGM). Multicenter prospective cohort study of pregnant women with T1D in Spain. We evaluated HbA1c and time spent within (TIR), below (TBR) and above (TAR) the pregnancy-specific glucose range 3.5-7.8 mmol/L. Adjusted models were performed for adverse pregnancy outcomes including baseline maternal characteristics and center. 112 women were included (HCL n=59). Women in the HCL group had a longer duration of diabetes and higher rates of prepregnancy care. There were no between-group differences in HbA1c in any trimester. However, in the second trimester, MDI users had a greater decrease in HbA1c (-6.12±9.06 vs. -2.16 ±7.42 mmol/mol, p=0.031). No differences in TIR (3.5-7.8 mmol/L) and TAR were observed between HCL and MDI users, but with a higher total insulin dose in the second trimester (+0.13 IU/Kg/d). HCL therapy was associated with increased maternal weight gain during pregnancy (βadjusted 3.20 kg, 95%CI 0.90-5.50). Regarding neonatal outcomes, newborns of HCL users were more likely to have higher birthweight (βadjusted 279.0 g, 95% CI 39.5-518.5) and macrosomia (ORadjusted 3.18, 95% CI 1.05-9.67) compared to MDI users. These associations disappeared when maternal weight gain or third trimester HbA1c were included in the models. In a real-world setting, HCL users gained more weight during pregnancy and had larger newborns than MDI users, while achieving similar glycemic control in terms of HbA1c and TIR.