Published on November 13, 2018

5 Facts About Gestational Diabetes

Paul D. Bobby, MD, Director, Maternal-Fetal Medicine

Pregnant woman in fall/winterWhat is Gestational Diabetes?

Gestational diabetes, or diabetes mellitus, is a type of diabetes during pregnancy. Gestational diabetes, unlike type 1 diabetes, is not caused by the body making too little insulin. Rather, a hormone made by the placenta prevents your body from using the insulin as it should. This is known as insulin resistance. As a result, glucose (blood sugar) accumulates in your blood instead of being absorbed by your body’s cells.

The good news? The symptoms of gestational diabetes usually disappear after delivery. However, sometimes they don’t or you might have an increased risk of developing type 2 diabetes later in life.

Here are 5  gestational diabetes basic facts: 

  1. A “temporary” diabetic state, gestational diabetes (GDM) is caused by the effects of pregnancy upon glucose metabolism
  2. GDM is the most common medical problem in pregnancy, affecting 5-9% of pregnancies.
  3. Mothers with risk factors for diabetes (see list) have a higher chance of developing GDM. However, GDM can develop in any mother!
  4. If gestational diabetes goes untreated and unrecognized, GDM can lead to complications in pregnancy for mother and child (see list). But the condition is easily treated- and the likelihood of complication can be greatly reduced with management
  5. GDM is easily diagnosed, with a two-stage process. Screening is usually performed at 24-28 weeks gestation using a glucose “challenge” test- that requires a single blood draw 60 minutes after a standard, liquid oral glucose load. Women with elevated glucose levels on the screening test undergo glucose “tolerance” testing, which is a more complicated test.

Here are 5 things you might not know about gestational diabetes: 

  1. The overwhelming majority of mothers with diabetes during pregnancy will be effectively managed with simple dietary changes. Only a relatively small number of pregnant women will require medication.
  2. Insulin- either made by the mother’s body, or administered as an injection- does not cross the placenta. The fetus has to make its own!
  3. Over time, high blood glucose in the mother leads to high insulin levels in the baby. Newborns ingest very little in the first days after birth. This is why blood glucose can fall to a dangerous level after birth in infants of some diabetic mothers.
  4. Mothers with risk factors for gestational diabetes are best screened twice during pregnancy- once at entry into prenatal care and again at about 28 weeks.
  5. Women with GDM have an increased risk for developing diabetes mellitus later in life and will be recommended for special long-term follow-up. There is a lot of research being performed to learn the best way to reduce this risk, so it is important to share this history with your doctor.

What are the risk factors for gestational diabetes?


1. Being overweight or obese
2. Having had a prior pregnancy with gestational diabetes
3. Family history of diabetes
4. Age (older = higher risk!)
5. Ethnicity

What happens if gestational diabetes goes untreated?


1. Excessive fetal growth
2. A scheduled cesarean delivery
3. Complicated vaginal birth
4. Low blood glucose in newborn
5. Difficulty breathing in newborn 

How does gestational diabetes glucose testing work?


1. You'll be on a required unrestricted diet for 3 days (>150g of carbohydrate per day) prior to your test.
2. Your test will be performed after an overnight fast of 8-14 hours. 
3. Your fasting blood glucose is measured before ingesting 100 grams of standard, liquid, oral glucose.
4. You'll remain seated while your blood glucose levels are drawn 1- , 2- and 3-hours after ingesting the glucose. 
5. If your results show that your measurements exceed the norms, you'll be given an appropriate gestational diabetes diagnosis.