If the patient showed borderline glucose intolerance (BGI), they used to be treated as a diabetic. However, as the uterus expands during pregnancy, excretion from the stomach is disturbed and the frequency of BGI increases. If GTT is performed for pregnant women, frequency of BGI increase up to 50% and BGI does not mean glucose intolerance during pregnancy. Instead of BGI, gestational diabetes mellitus demonstrates glucose intolerance during pregnancy. Gestational diabetes develops diabetes frequently after delivery and requires strict Follow-up.