1. Patient Resources
  2. Pregnancy Complications
  3. Diabetes


Gestational diabetes mellitus (GDM) is the second most common (after pre-eclampsia) medical complication of pregnancy. GDM is relatively common, affecting 3 to 6 percent of all pregnant women. There are certain complications of pregnancy that are more common among GDM pregnancies, but the chance of any of these occurring can be minimized by good medical management during pregnancy. These complications include larger than average babies, cesarean section deliveries and neonatal problems such as low blood sugar or calcium levels. If GDM is recognized and medically managed, significant risks are minimal and both the mother and baby should do well.

Screening for Gestational Diabetes

It is recommended that all pregnant women be screened for GDM unless they are known to have diabetes mellitus before pregnancy. The screening test for GDM is performed via a blood sample drawn to measure the blood sugar (glucose) level one hour after drinking a sweet carbohydrate solution. If the screening test glucose is too high, the definitive diagnostic test for GDM , a three-hour glucose tolerance test, is done. Screening one-hour test for GDM is performed at 24-28 weeks gestation, unless the woman has other risk factors for GDM such as strong family history of diabetes, a prior unusually large baby, a history of GDM in a prior pregnancy, is 35 years or older or is significantly heavier than average. If any of these risk factors apply to the patient, her doctor may want her to have the one-hour screening test earlier in pregnancy. The woman does not need to be fasting before the one-hour screening test. However, if the three-hour test is necessary, she needs to have fasted (not eaten) for eight to 10 hours before starting the test.

If the glucose tolerance test is positive indicating that the patient has GDM, dietary counseling and home testing of finger stick blood sugar levels are necessary. The majority of GDM patients can achieve satisfactory blood glucose levels with an appropriate diet and exercise (e.g., walking after meals).  If diet and exercise does not result in satisfactory blood glucose levels, medications (oral tablets or insulin injections) may be necessary.

Women with GDM can anticipate delivering near their due date and delivering normally (vaginally). Cesarean section delivery is more common in GDM pregnancies, but the risk of this can be reduced by good glucose control.

The infants of women with GDM are tested in the nursery to make sure that the baby’s blood sugar levels remain in the normal range. Typically five to six weeks after delivery, a woman with GDM may need to have a follow up glucose tolerance test performed to be sure that the GDM has resolved. Women who had a pregnancy complicated by GDM are at an increased risk the developing type 2 (noninsulin-dependent) diabetes later in life. It is recommended after a GDM complicated pregnancy, the woman continue to follow a healthy diet, keep an active life style and maintain her weight as close to normal as possible. Additionally, a woman who has had GDM in a prior pregnancy should be tested by her primary physician every one to two years to be sure that type 2 diabetes has not developed.