In women with type-1 diabetes, the prevalence of maternal and fetal complications is high despite the overall adequate blood glucose control (HbA1c < 7%). Further improvements are hampered by the high incidence of maternal hypoglycaemia, including coma, especially during the first trimester of pregnancy. The reasons for this include the intensified insulin treatment, the decrease in hypoglycaemia awareness and the increase in glucose fluctuations. A further improvement of glucose control would provisionally seem possible only by using short-acting insulin analogues. These agents are currently under investigation. Continuous subcutaneous glucose measurements early in pregnancy show considerable glucose fluctuations despite almost normal HbA1c values. Moreover, they often reveal a hypoglycaemic event that the pregnant woman has not recognised. It is possible that these glucose fluctuations, rather than the too high average blood glucose levels, are responsible for congenital malformations and fetal macrosomia. Neonatal hypoglycaemia is associated with poor psychoneurological development. This relationship has not been established for maternal hypoglycaemia during pregnancy.