Physiological changes in insulin resistance in human pregnancy: longitudinal study with the hyperinsulinaemic euglycaemic clamp technique

Abstract

Objective: To perform measurements of insulin resistance serially in pregnancy and after childbirth in normal women.

Design: Longitudinal study.

Setting: Teaching hospital.

Methods: Ten normal women were studied using the hyperinsulinaemic euglycaemic clamp technique before pregnancy, at 16, 26 and 36 weeks gestation, and 8 weeks after delivery. All women breastfed their infants. Insulin resistance was measured by the glucose infusion rate required to maintain the plasma glucose at 4.5 mmol/l.

Results: There was a progressive increase in insulin resistance in all women as pregnancy progressed. The increase in resistance was most marked between 16 and 26 weeks of gestation, with only minimal progression thereafter. Lactation does not alter insulin resistance.

Conclusion: The timing and extent of changes in insulin resistance are of physiological importance because they affect all classes of maternal and fetal substrates.