Pregnancies complicated by diabetes mellitus (DM) include pregestational DM and gestational DM, defined as carbohydrate intolerance of variable severity first detected during pregnancy. DM leads to poor pregnancy outcome. The aim of treatment is to control maternal hyperglycaemia and to imitate postprandial insulin release. Rapid-acting insulin analogues are suitable therapeutic candidates, as they are able to reduce postprandial hyperglycaemia (predictive of adverse pregnancy outcome). There is no excess risk of adverse fetal or maternal outcomes when compared with regular insulin. Data suggest that rapid-acting insulin analogues do not transfer to human placenta. Because of the reduced risk of hypoglycaemia and improved postprandial and overall glucose control, insulin analogues could be considered the rapid-acting insulin choice during pregnancy.