A comparison of the safety and effectiveness of insulin aspart with other bolus insulins in women with pre-existing Type 1 diabetes during pregnancy: A post hoc analysis of a prospective cohort study

Aims: The safety and efficacy of insulin analogue insulin aspart (IAsp) have been demonstrated in a randomised clinical trial in pregnant women with Type 1 diabetes (T1D), and IAsp is widely used during pregnancy. The aim of this study was to assess glycaemic control and safety of IAsp versus other bolus insulins in Type 1 diabetic pregnancy in a real-world setting. Methods: This was a post hoc analysis of a prospective cohort study of 1840 pregnant women with T1D, treated with IAsp (n = 1434) or other bolus insulins (n = 406) in the Diabetes Pregnancy Registry. The primary (composite) outcome was the proportion of pregnancies resulting in major congenital malformations or perinatal or neonatal death. Secondary outcomes included all HbA_1c values measured immediately before and during pregnancy and major hypoglycaemia, as well as abortion, pre-eclampsia, pre-term delivery, large for gestational age at birth, stillbirth and fetal malformations. Results: There were no significant differences found in any of the pregnancy outcomes between treatment with IAsp and other bolus insulins in either the crude or propensity score-adjusted analyses. However, maternal HbA_1c was lower in the IAsp group at the end of the third trimester (adjusted difference, −0.16% point [95% CI −0.28;−0.05]; −1.8 mmol/mol [95% CI −3.1;−0.6]; p = 0.0046). Conclusions: No significant differences in safety or pregnancy outcomes were demonstrated when comparing treatment with IAsp versus other bolus insulins in women with T1D during pregnancy. The observed improvement in HbA_1c with IAsp in late pregnancy should be confirmed in other studies.