Gestational diabetes mellitus (GDM) is a form of diabetes that can develop in pregnant people. It is fairly common and can occur if a person is unable to make enough insulin during pregnancy.

Diabetes is a condition that occurs when a person’s blood glucose levels are too high. Glucose is a type of sugar in food and drinks that the body uses for energy.

A person’s body uses the hormone insulin to transport glucose from food to cells. If a person’s body does not make enough insulin, glucose levels can build up in the bloodstream. This can lead to health issues, such as heart disease and stroke.

GDM is a condition that can occur during a person’s pregnancy. It can develop in people who have never had diabetes before.

This article examines how common GDM is, its risk factors, and how people can treat it.

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According to the Centers for Disease Control and Prevention (CDC), GDM occurs in 2⁠–10% of pregnancies in the United States each year.

A study from 2020 noted that GDM is a common condition that affects 9⁠–⁠25% of pregnancies worldwide.

There are disparities in the prevalence of GDM among racial and ethnic groups. According to a 2022 study, the prevalence of GDM is:

  • 4.8% among non-Hispanic Black females
  • 6.6% among Hispanic females
  • 5.3% among non-Hispanic white females

More research from 2022 found that people identifying as Asian or Pacific Islander and Hispanic or Latina had the highest rates of GDM. Researchers suggest this may be due to disparities in prenatal care and testing for hyperglycemia (high blood glucose).

Health inequities affect all of us differently. Visit our dedicated hub for an in-depth look at social disparities in health and what we can do to correct them.

GDM develops when a person’s body cannot make enough insulin during pregnancy.

When a person is pregnant, their body undergoes certain changes. These changes can cause their cells to be unable to use insulin effectively. This is called insulin resistance.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) notes that all pregnant people have some insulin resistance during late pregnancy. Although most people can generate enough insulin to counteract the insulin resistance, some cannot. These people may develop GDM.

Certain risk factors make a person more likely to develop GDM, including:

  • having obesity
  • being overweight
  • family history of diabetes
  • having insulin resistance before pregnancy
  • being over 25
  • having had GDM during a previous pregnancy
  • a previous pregnancy where the baby weighed more than average
  • high blood pressure or heart disease
  • polycystic ovary syndrome (PCOS)
  • prediabetes, where blood glucose levels are higher than usual
  • being a member of a race or ethnic group with a higher rate of diabetes, possibly as a result of disparities in healthcare and socioeconomic factors

Learn more about risk factors for GDM.

GDM generally has no symptoms. If a person does have symptoms, they may be mild. They can include being thirstier than usual or needing to urinate more often.

Having GDM can put a person at risk of certain health issues. These include:

Type 2 diabetes can cause a person to develop additional health issues, such as:

If a person develops GDM, the fetus is also at risk of certain health issues. These can include:

Being born to a person with GDM also increases a baby’s chances of developing obesity or diabetes later in life.

A doctor generally tests a person for GDM between weeks 24⁠ and 28 of pregnancy. If a person has risk factors or a family history of diabetes, a doctor may test them earlier.

There are two blood tests a doctor can use to diagnose GDM. A person may get one or both of these tests.

Glucose challenge test

The glucose challenge test involves a healthcare professional taking a person’s blood 1 hour after they drink a liquid containing glucose.

If a person has a blood glucose level of 140 milligrams per deciliter (mg/dL) or more, they may need an oral glucose tolerance test (OGTT). If their blood glucose level is 200 mg/dL or higher, they may have type 2 diabetes.


Before an OGTT, a person should fast for 8 hours. During the OGTT test, a healthcare professional will take a person’s blood. A person will then drink a liquid containing glucose.

After the person drinks the glucose-containing liquid, a healthcare professional takes their blood every hour for 2–3 hours. If a person has high glucose levels on two or more of these tests, they have GDM.

A person can treat their GDM by:

  • Performing moderately intense exercise: Moderate physical activity can help a person maintain healthy blood glucose levels. It can also reduce a person’s chance of developing type 2 diabetes later in life. A doctor can talk with a person about exercising safely.
  • Checking their blood glucose frequently: A person needs to monitor their blood glucose to ensure it remains within the target range.

If a person cannot manage their blood glucose levels using exercise and healthy eating, a doctor may prescribe medication.

Learn about blood sugar goals and how to test at home.

A person may be able to prevent GDM by exercising and maintaining a moderate weight before conceiving.

If a person is already pregnant, they should not try to lose weight. A person should gain some weight during pregnancy, although not too quickly. They can speak with a doctor about how much weight gain is suitable for them.

Learn more about pregnancy weight gain.

A person should consult a doctor if they develop unusual or concerning symptoms during pregnancy.

If a person experiences any symptoms of preeclampsia, they should seek immediate medical attention. Symptoms of preeclampsia include:

A person’s blood glucose levels generally return to typical levels after a person has a baby. However, the CDC notes that around 50% of people with GDM go on to develop type 2 diabetes.

A person can reduce their risk of developing type 2 diabetes by making lifestyle changes. This can include losing weight if they are overweight or exercising regularly.

GDM is a form of diabetes that develops during pregnancy. It is fairly common and affects 2–10% of pregnancies in the U.S.

Certain risk factors increase a person’s chances of developing GDM, such as being overweight.

A person with GDM is at higher risk of other health conditions, including preeclampsia and depression. The fetus is also at risk of premature birth. Both parent and baby have an increased risk of developing type 2 diabetes later in life.

A person can manage GDM with a healthy diet and exercise. A doctor can also prescribe medication.

GDM generally goes away after a person gives birth. However, some people can go on to develop type 2 diabetes.

A person should speak with a doctor if they notice any unusual symptoms during pregnancy. They should seek immediate medical attention if they have any symptoms of preeclampsia.