A diabetic disorder in early pregnancy is the cause of early abortions, pregnancy complications and birth defects of the child. After birth the risk to develop diseases of the metabolic syndrome in adulthood is significantly increased. Using a pregnant rabbit model, we induced an insulin dependent diabetes mellitus. The main findings of this work are: Maternal diabetes interferes with oocyte maturation, embryonic metabolism and developmental processes from the gastrulation onwards. Insulin-induced differentiation processes are mediated via the wnt/ß-catenin signaling system. Due to the lack of insulin, the induction of mesoderm-specific transcription factors is delayed. For mammalian gastrulation the insulin/IGF-system is essential. A lack of insulin in the embryo leads to serious developmental disorders as early as during the preimplantation period.