A type of diabetes first diagnosed during pregnancy. Gestational diabetes affects about 4% of all pregnancies, resulting in roughly 135,000 cases in the United States each year.
Gestational diabetes usually develops during the second or third trimester of pregnancy. Certain hormones released at that time work against the action of insulin and cause insulin resistance. Insulin resistance is a condition in which muscle and fat cells do not respond normally to insulin, so extra insulin is required to move glucose from the blood into the cells. If the pancreas is unable to produce enough insulin to meet this increased demand, gestational diabetes develops. Women with gestational diabetes are at increased risk of giving birth to babies with respiratory problems or high birth weights.
Gestational diabetes is most likely to affect women who are over the age of 25, are overweight, have a close family member with diabetes, or belong to an ethnic group at high risk for diabetes (African-Americans, Asian-Americans, Hispanic Americans, and Native Americans fit into this category). These women should be screened for gestational diabetes between the 24th and 28th week of pregnancy.
Screening consists of a oral glucose tolerance test, or OGTT, which is designed to determine how well a person’s body handles glucose. The woman drinks 50 grams of pure glucose dissolved in water. One hour later, her blood glucose level is checked. A blood glucose level of 140 mg/dl or higher indicates that the woman may have diabetes, and another test is done. In this test, the woman fasts, then ingests 100 grams of glucose. Her blood glucose level is checked up to four times: once before ingesting the glucose and at one hour, two hours, and three hours afterward. If any two of these values is above a certain level (105 mg/dl while fasting, 190 at one hour, 165 at two hours, or 145 at three hours), then the diagnosis of diabetes is confirmed.
Women diagnosed with gestational diabetes must strive to keep their blood sugar levels under control. Some women only need to change their diets. Others may need to exercise regularly or inject insulin. Doctors do not typically prescribe oral drugs as a treatment for gestational diabetes.
Gestational diabetes usually disappears when the stress of pregnancy is over. However, women who have had gestational diabetes are more likely to develop it again during future pregnancies. They are also at a higher risk for developing Type 2 diabetes later in life. For this reason, women who have had gestational diabetes should continue to eat a healthy diet, avoid gaining weight, and exercise regularly after giving birth.