Abstract
Objective: To show the relation of prolactin with the incidence of glucose intolerance in pregnancy.
Methodology: This study was carried out on thirty Sudanese pregnant ladies suffering from gestational diabetes mellitus, 30 ones with impaired glucose tolerance and 30 control ones with normal glucose tolerance. All subjects overnight fasted before the test. A fasting blood sample was drawn at 6.00 a.m. Thereafter, 75g oral glucose dissolved in 200 cc water was given for each, waiting for two hours and then another blood sample was drawn. Fasting and 2-h, after 75g glucose load, plasma glucose concentrations (FBS and 2h-BS) were estimated by glucose oxidase method. The concentrations of serum insulin in the fasting sample (0 min.) and in the 2 hour after 75g glucose load sample (120 min.) were measured with a specific immunoradiometric assay. The concentrations of serum prolactin (120 min.) were measured with a specific radioimmunoassay.
Results: There were no significant differences among levels of fasting serum insulin of the three studied groups (p>0.05) while, the mean level of 2h-serum insulin of the GDM group was significantly lower than that of the IGT and control groups (p <0.005). Results of serum prolactin of the control group in the first, second and third trimester showed that prolactin increases progressively as pregnancy advances (p <0.0001). Results of serum prolactin of the GDM, IGT and control groups in the third trimester showed that no two groups were significantly different (p>0.05) although the control group recorded the highest mean level of serum prolactin.
Conclusion: Prolactin increases progressively as pregnancy advances, reaching a peak in the third trimester when many pregnant ladies may develop gestational diabetes due to the state of insulin resistance which may occur although there is no evidence that prolactin may be directly incorporated with the pathogenesis of glucose intolerance in pregnancy. A decline in insulin secretion may lead to a decline in prolactin since insulin stimulates both acute secretion and de novo synthesis of decidual prolactin.