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Gestational Diabetes: What You Should Know


Pregnancy may put you at risk of this form of diabetes. Find out more

Updated on December 9, 2015.

By Eirish Sison 


From morning sickness to insomnia, pregnancy has its share of annoyances. But for as many as 9% of pregnant women each year, a more serious issue will occur: gestational diabetes mellitus or GDM, a temporary form of diabetes that occurs in pregnancy. GDM causes your blood glucose (sugar) levels to be abnormally elevated, which can cause serious consequences for you and for the baby. 

How will I find out if I have GDM?

Most pregnant woman will be screened for GDM between 24 and 28 weeks in a test that involves drinking a sugary drink, then having a blood test to check their glucose levels 1 hour later. If the results are abnormally high, another glucose challenge test is recommended, called an oral glucose tolerance test (OGTT). If the results of this test are abnormal, a GDM diagnosis is confirmed.

Women at high risk will likely be screened for diabetes at their first prenatal exam. You’re at high risk if you’re very overweight, have had gestational diabetes before, have a strong family history of diabetes, or have glucose in your urine during a routine prenatal check.

Women who have prediabetes; have high blood pressure (hypertension); are over the age of 25; are of Hispanic, African American, Native American or Asian descent; or who previously gave birth to a baby that weighed more than 9 pounds are at average risk for GDM, and will definitely be tested. If you don’t have any of these risk factors, you’re considered to be at low risk and may not be tested.


How does GDM happen?

The placenta, the organ that transfers hormones and nutrients from you to your baby via the umbilical cord, is responsible for your baby's growth and development. Hormones in the placenta block the action of insulin, a regulatory hormone that controls the amount of glucose in the blood. This dilemma, called insulin resistance, forces the pancreas to produce extra insulin for the body to function properly. Normally, your body can meet this challenge and your blood sugar levels normalize. But when you have GDM, your body doesn't produce enough insulin to combat insulin resistance, resulting in high blood sugar levels, or hyperglycemia.

What are the signs of GDM?

For most pregnant women, GDM does not cause any noticeable physical symptoms. Rarely you may experience increased thirst or increased urination.

How does GDM affect moms and babies?

Because gestational diabetes develops later in pregnancy, after your baby's organs have formed (around week 13), it does not cause serious birth defects. However, poorly controlled blood sugar is associated with many complications:

In babies, poorly controlled blood sugar can cause:

    • High birth weight. High glucose levels cause increased growth for the fetus, also known as macrosomia. Large fetal growth is associated with increased C-section rates and birth trauma. 
    • Low blood sugar at birth.Your baby is more likely to have low blood sugar during the first few days of life, as it will no longer be receiving excess blood sugar from you.  
    • Breathing problems. Babies born early may experience respiratory distress syndrome — a condition that makes breathing difficult. Babies with this syndrome may need help breathing until their lungs become stronger.
    • Increased risk for obesity and type 2 diabetes in childhood and adulthood.Some studies have suggested that the fetal environment can affect health later on in life.

In mothers, poorly controlled blood sugar can cause:

    • Increased risk for developing type 2 diabetes later in life. Women who have had gestational diabetes have a 35 to 80% chance of developing diabetes in the next 10 to 20 years, according to the Centers for Disease Control and Prevention (CDC). Women with gestational diabetes should get their blood sugar tested for type 2 diabetes after the birth of their child and then periodically thereafter.
    • Increased risk of gestational diabetes in future pregnancies. There’s a 66% chance that it will recur.
    • High blood pressure.
    • Preterm (early) labor
    • Preeclampsia, a condition characterized by hypertension (high blood pressure) during pregnancy. 
    • Increased risk for stillbirth.

How is GDM managed and treated?

Treating GDM means taking steps to keep your blood sugar levels in a healthy target range. To do this:

  • Monitor your blood sugar levels in the morning and after meals. Use our Sugar Sense app (for iOS and Android) to record and track your numbers. National Institute of Diabetes and Digestive and Kidney Diseases provides the following chart of blood glucose targets for most women with gestational diabetes. Talk with your doctor about whether these targets are right for you. 

Upon awakening

Blood glucose not above 95mg/dL

1 hour after a meal

Not above 140mg/dL

2 hours after a meal

Less than 120mg/dL
  • Eat a healthy, balanced diet to control blood sugar and avoid excessive weight gain. Distribute meals evenly throughout the day and restrict sugar intake. Most women with gestational diabetes meet with a dietitian or diabetes educator to create an individualized gestational diabetes diet.
  • Exercise at a moderate level every day. Make sure to check with your provider about your workout routine.

If you’re unable to manage your glucose with diet and exercise, you may need to take medication; your provider will help you decide. 

Women with GDM may have their babies monitored more frequently, including more ultrasounds and an exam called a non-stress test — especially if they have to take medication to control their GDM. Some GDM patients are referred to high-risk ob/gyns for care.

Although managing GDM sounds like a lot of work, studies have shown that keeping your blood glucose in a normal range has a big pay-off. The 2005 Australian Carbohydrate Intolerance study showed that treatment of GDM resulted in fewer high–birth weight babies, less difficulty delivering, fewer fetal deaths, and fewer cases of preeclampsia, a serious pregnancy complication. A second study by the NIH in 2009 showed that treatment of GDM resulted in fewer C-sections in women with this condition. Working with your provider can help you have the best outcome for both you and your baby.

When does GDM go away?

In most cases, your blood sugar will return to normal soon after delivery. However, even though GDM resolves with the birth of your baby, it is associated with developing diabetes type 2 later in life. Your child may also have risks of developing health problems later in life. 

How can I prevent GDM?

You may not be able to prevent GDM, but maintaining a healthy lifestyle and weight can help. If you’re thinking about getting pregnant, it’s a good idea to talk to your ob/gyn about preconception counseling — a chance to talk about maximizing your health prior to conception, which may help to reduce pregnancy complications.

Healthy habits may also reduce your risk of having gestational diabetes during future pregnancies and of developing type 2 diabetes down the road.


Published on May 31, 2011. 

Eirish Sison is a health writer based in the San Francisco Bay Area.

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Reviewed by Elisabeth Aron, MD, MPH, FACOG on July 18, 2015.