Gestational diabetes is diabetes mellitus that develops in women for the first time during pregnancy. Some women found to have gestational diabetes actually may have had mild diabetes before pregnancy that was not diagnosed.
Gestational diabetes is caused by a change in the way a woman's body responds to insulin during pregnancy. Insulin is a hormone. It moves glucose out of the blood and into the body’s cells where it can be turned into energy. During pregnancy, a woman's cells naturally become slightly more resistant to insulin’s effects. This change is designed to increase the mother’s blood glucose level to make more nutrients available to the baby. The mother's body makes more insulin to keep the blood glucose level normal. In a small number of women, even this increase is not enough to keep their blood glucose levels in the normal range. As a result, they develop gestational diabetes.