Pregnancy is attended by extensive hormonal readjustments on the part of the mother. Almost every endocrine tissue participates in adaptive changes that maintain the metabolic state of the woman during normal pregnancy. Endocrinologic and metabolic adaptations characterizing pregnancy in women with normal carbohydrate metabolism also impinge upon the metabolism of the diabetic during pregnancy. In the diabetic woman the impairment of metabolism which follows the modifications of endocrinologic adaptations induces a compromised metabolic "milieu" in both the foetal blood and amniotic fluid in which swallows the fetus, promoting several damages according to the gestational age in the conceptus. Disturbances of intermediary metabolism undoubtedly play a major role in the etiology of complications of diabetic pregnancy. However an increasing amount of evidence is accumulating that suggests that abnormalities of immune function may also be operative in both the mother and fetus as well as in placenta. Finally there is limited information on the long-term prognosis of infants born to mothers with pre-gestational and gestational diabetes mellitus. Follow-up studies have mainly focused on two aspects: the risk of appearance of diabetes later in life, and psychosomatic development. Genetic aspects and the role of metabolic disorders during pregnancy must be once again emphasized.