Rapid-acting insulin analogs are increasingly used during type 1 diabetic pregnancy. They may assist women to safely optimize glucose control (1,2), but little is known about their pharmacokinetics and reproducibility in pregnancy. Using a unique data set of 1,300 plasma insulin samples collected under strictly observed experimental conditions, we explored the relationship between aspart pharmacokinetics and clinical and demographic factors. We also assessed reproducibility both within and between pregnant women using continuous subcutaneous insulin infusion (CSII).