During a pregnancy metabolic and hormonal modifications aimed at survival and fetal growth were observed, many of which regard glucose metabolism and insulin secretion. During pregnancy insulinemia progressively rises while insulin action at hepatic level falls with a consequent development of insulin resistance. This condition, connected mainly to contra-insular activity of pregnancy hormones, may cause, in susceptible pregnant women, an impaired glucose tolerance or gestational diabetes or may cause, in diabetic women, a worsening of metabolic control. At same time diabetes may negatively influence the embryo , fetus and perinatal events. The nutrients, used by the fetus mainly as a source of energy, through the placenta or directly by means of a mechanism of "facilitated transport" (glucose), or by means of a system of "active transport" requiring energy (amino acids). In particular, maternal hyperglycemia constantly determines a fetal hyperglycemia which is corrected by increasing insulin secretion with a consequent fetal hyperinsulinism. Modified concentration of fetal nutrients and hyperglycemia in particular, are through responsible, in diabetes, for the embryo-fetal pathology of which the man features are malformation, hypertropic cardiomyopathy, placental insufficiency, pre-eclampsia, macrosomia, fetal intrauterine death, delay in fetal lung maturity, hypoglycemia, and neonatal hypocalcemia.
In conclusion: strict metabolic control of pre-pregnancy diabetes already at conception and the treatment of gestational diabetes are the best way to protect fetal-maternal health in diabetic pregnancy.