Insulin action does not change during the menstrual cycle in normal women.

Normal women have alterations in carbohydrate metabolism during pregnancy and when taking oral contraceptives, and clinical observations suggest that diabetic women need more insulin during menstruation. We, therefore, studied insulin action in normal women during the menstrual cycle in the follicular, luteal, and menstrual phases. Glucose tolerance was similar at all three times. Specific insulin receptor binding to monocytes did not change during the menstrual cycle. Euglycemic insulin clamp studies at four different insulin infusion rates (15, 40, 120, and 240 mU/M2 X min) showed no differences in insulin sensitivity or responsiveness throughout the menstrual cycle, and hepatic glucose output did not change. These studies suggest that if insulin action is impaired during menstruation in diabetic women it is because of factors that are not detected in normal women.