Influence of lactation on oral glucose tolerance in the puerperium.

The influence of endogenous hyperprolactinaemia on oral glucose tolerance in normal women post-partum was studied. An oral glucose tolerance test (OGTT) was performed 8 weeks after delivery in 23 women, 13 of whom were breastfeeding. The lactating women had significantly higher plasma prolactin values before and during the OGTT than the non-lactating women (P less than 0.005). Fasting values of serum FSH, LH, progesterone and plasma glucagon were similar in the two groups. The non-lactating women had higher fasting concentrations of serum oestradiol (P less than 0.0005), plasma glucose (P less than 0.05) and insulin (P less than 0.05) than the lactating women. After oral glucose no differences were found between lactating and non-lactating women in changes in plasma glucose, insulin and glucagon concentrations. It is concluded that lactating women 8 weeks post-partum do not have an impaired OGTT compared to non-lactating women despite elevated plasma prolactin levels.