A type of diabetes mellitus that can occur when a woman is pregnant. In the second half of the pregnancy, the woman may have glucose (sugar) in the blood at a higher than normal level. However, when the pregnancy ends, the blood glucose levels return to normal in about 95 percent of all cases.

Gestational diabetes is a type of diabetes (when blood sugar levels become too high) which develops during pregnancy. It can be treated, and usually disappears after pregnancy.

a high blood glucose level that is discovered during pregnancy. As pregnancy progresses, there is an increased need for glucose for the developing baby. Additionally, hormone changes during pregnancy affect the action of insulin, resulting in high blood glucose levels. Usually, blood glucose levels return to normal after childbirth. However, women who have had gestational diabetes are at increased risk of developing type 2 diabetes later in life.

A type of diabetes mellitus that develops only during pregnancy and usually disappears upon delivery, but increases the risk that the mother will develop diabetes later. GDM is managed with meal planning, activity, and, in some cases, insulin.