Gestational Diabetes

The following information is of a general nature only and should not be substituted for medical advice or used to alter medical therapy. It does not replace consultations with qualified healthcare professionals to meet your individual medical needs.

What is Gestational Diabetes?

Gestational diabetes (sometimes referred to as GDM) is a form of diabetes that occurs during pregnancy and usually goes away after the baby is born. It is diagnosed when higher than normal blood glucose levels first appear during pregnancy. Between 12% and 14% of pregnant women will develop gestational diabetes and this usually occurs around the 24th to 28th week of pregnancy.

All women should be tested for gestational diabetes by taking a special blood test. Women who have one or more of the risk factors listed below are advised to have a diabetes test when pregnancy is confirmed then again at 24 weeks if diabetes was not detected in early pregnancy.

While maternal blood glucose levels usually return to normal after birth, there is an increased risk for the mother developing type 2 diabetes in the future. The baby may also be at risk of developing type 2 diabetes later in life.

Read more in our Understanding gestational diabetes fact sheet.

Who is at Risk?

You are at risk of developing gestational diabetes if you:

  • are over 40 years of age
  • have a family history of type 2 diabetes
  • are overweight
  • are from an Aboriginal or Torres Strait Islander background
  • are from a Vietnamese, Chinese, middle eastern, Polynesian or Melanesian background
  • have had gestational diabetes during previous pregnancies.

What Causes Gestational Diabetes?

In pregnancy, the placenta produces hormones that help the baby to grow and develop. These hormones also block the action of the mother’s insulin. This is called insulin resistance. Because of this insulin resistance, the need for insulin in pregnancy is 2 or 3 times higher than normal. If the body is unable to produce this much insulin, gestational diabetes develops.

Managing Gestational Diabetes

Gestational diabetes is managed by monitoring blood glucose levels, adopting a healthy eating plan and performing regular physical activity.

Your health care team can help you with blood glucose monitoring, healthy eating and physical activity. Click here for a list of health professionals that can be part of your health care team. More information about blood glucose monitoring can be found here.

Gestational diabetes can often initially be managed with healthy eating and regular physical activity. However, for some women with gestational diabetes, insulin injections will be necessary for the rest of the pregnancy. Approximately 10 – 20% of women will need insulin, however, once the baby is born insulin is no longer needed. This is safe for both you and your baby.

Blood glucose lowering tablets are generally not used in pregnancy.

After the baby is born, gestational diabetes usually disappears. A special blood glucose test (Oral Glucose Tolerance Test) (OGTT) is performed six weeks after delivery to ensure that blood glucose levels have returned to normal. However, women who have had gestational diabetes have an increased risk of developing type 2 diabetes later in life and should be tested for diabetes at least every 2 – 3 years.

Reducing the Risk of Developing Type 2 Diabetes

While maternal blood glucose levels usually return to normal after birth, there is an increased risk for the mother developing type 2 diabetes in the future. To reduce your risk or delay the development of type 2 diabetes after your baby is born, keep in mind the following important points:

  • Maintain or achieve a healthy weight. Balancing food intake with activity levels is the best way to maintain or reduce any excess body weight.
  • Eat healthily. Limit saturated fat. Choose lean meat, skinless chicken and low fat dairy foods. Limit processed and fried foods. Eat plenty of vegetables, legumes, fruits, wholegrain breads and cereals.
  • Be physically active. Aim to include at least 30 minutes of moderate intensity physical activity on most days. You should discuss your physical activity plans with your doctor prior to starting any exercise regime.
  • Check blood glucose levels. It is important to have your blood glucose tested every 1-2 years. Discuss this with your doctor.


The NDSS has a dedicated webpage for gestational diabetes. The webpage includes information, resources and support about gestational diabetes and information about the gestational diabetes register. To visit the Gestational Diabetes webpage, click here.

You can also look at copies of our gestational diabetes booklets in the Gestational Diabetes Resources section. These have been translated into five different languages: Arabic, Turkish, Vietnamese, Traditional Chinese and Simplified Chinese. You can find those copies in the Translated Resources section.

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