Experimental chemical diabetes and pregnancy in the rat. Evolution of glucose tolerance and insulin response.

The effect of pregnancy on the course of experimental chemical diabetes (CD) has been studied in the rat. Glucose tolerance tests (0.5 g/kg i.v.) have been performed serially in the virgin state (2 mo), late pregnancy (20.5 day of gestation), and 1 and 2 mo after delivery, in control and in CD female rats. During gestation in the controls basal plasma glucose is decreased, and plasma glucose levels after glucose load, and also lower than levels found in the virgin state. Glucose tolerance is not significantly affected. Nevertheless, glucose-induced insulin secretion in pregnant animals is increased compared with the virgin state. Glucose tolerance remains unchanged 1 and 2 mo postpartum, but insulin response to glucose becomes significantly lower than in the virgin state. In the pregnant CD rats basal plasma glucose is decreased, but plasma glucose levels after glucose load are similar to values found in the virgin state, thus suggesting decreased glucose tolerance. Glucose-induced insulin secretion is increased compared with the virgin state. Glucose tolerance remains deteriorated 1 and 2 mo postpartum, but insulin secretion is no longer significantly different. These findings indicate that in CD female rats glucose tolerance is and remains deteriorated by pregnancy, while in normal female rats it is and remains unchanged. Thus, despite increased insulin response to glucose during late gestation in the CD rats, the diabetogenicity of pregnancy is confirmed with this experimental model.