Prolactin and glucose tolerance in normal and gestational diabetic pregnancy.

The relationship between the deterioration of glucose tolerance and plasma prolactin (PRL) levels was investigated in 15 normal pregnant women and in 15 women with gestational diabetes mellitus. Oral glucose tolerance tests were performed in late pregnancy and postpartum, and the insulin, glucagon, and PRL responses were measured. In late pregnancy the gestational diabetics revealed significantly elevated fasting glucose levels compared with the normal pregnant women and after the glucose challenge their insulin responses were significantly diminished and the suppression of glucagon less pronounced. These differences in glucose metabolism were markedly reduced early postpartum. There was no difference in basal PRL concentrations between the two groups neither in pregnancy nor postpartum. The PRL levels were not altered during the oral glucose tolerance tests and no correlation between the deterioration of glucose tolerance and the PRL concentrations could be demonstrated in either group. These results indicate that abnormal PRL levels are not of pathophysiologic importance for the development of gestational diabetes mellitus.