The effect of type-I diabetes on the quality of general movements (GMs) was studied longitudinally in 12 human fetuses. GMs were analysed at two-weekly intervals from 16 weeks until delivery. A pregnancy optimality-score and a diabetes optimality-score were used to cover the course of the pregnancy and delivery and the severity of diabetes. GMs of infants were analysed 1, 4-6, and 12-18 weeks after birth and the Bayley developmental test was performed at 10 months. All fetuses showed normal GMs at 16 weeks. From 20 weeks onwards until delivery five fetuses developed abnormal GMs. The diabetes optimality-score was significantly lower in the group with abnormal GMs (P = 0.018) whereas the pregnancy optimality-score did not differ between fetuses with normal and abnormal GMs. Our results indicate that type-I diabetes can have a negative impact on prenatally observed GMs. Consistently normal GMs indicate normal neurodevelopmental outcome at 10 months whereas in the group with abnormal GMs reduced Bayley-scores may occur.