Delayed emergence of movement patterns and disturbances in the development of behavioural states are often observed in the fetuses of diabetic women. The developmental course of specific fetal movement patterns was studied in 20 women with type-1 diabetes during the first trimester of pregnancy. The aim was to investigate whether maternal diabetes also has an effect on the rate of occurrence and temporal patterning of fetal movements. Real-time ultrasound recordings with a duration of 1 h were made once a week between the 7th and 17th week postmenstrual age in order to quantify fetal movements. The data were compared to those obtained in a group of uncomplicated pregnancies. The developmental trends in the occurrence of movement patterns were similar to those in the control fetuses, with the exception of startles. Before the 9th week of gestation, fetal movements occurred less frequently; this was related to the quality of maternal glucose control. After 12 weeks, the overall incidence was higher than in the control group, due to an increase in the incidence of breathing movements. The rate of breathing movements was generally slower than in the control group.