Fetal Growth and Glucose Metabolism in Diabetic Pregnant Rats

We have studied the effects of diabetes on fetal growth, glucose metabolism, lung maturation, and bone development in rats. Fetuses in diabetic rats showed decreased body weights and increased placental weights. A morphological study of the fetal pancreas suggested that the area of the islets was increased. Plasma insulin levels and pancreatic levels of insulin and somatostatin were decreased, while plasma glucagon levels were unchanged. The levels of glycogen, glycogen synthase activity and somatomedin-C were increased in the fetal liver. The serum transferrin levels were decreased and correlated with the reduced body weights. The levels of insulin and cortisol in the amniotic fluid and the weights of lungs were decreased. Levels of phosphatidylcholine (PC) in the lung and the abilities to synthesize PC and phosphatidylglycerol (PG) from glucose were decreased. The incidence of lumbar and cervical ribs was about 2–5 times higher than normal. Evidence of decreased ossification was also present. The fetuses of insulin-treated diabetic rats, in which blood glucose concentrations before and during pregnancy were rigidly controlled, showed dramatic improvement in all these parameters to values near to those of the controls.