BHC home - health and medical information for consumers

Health and medical information for consumers, quality assured by the Victorian government (Australia).

8 October, 2008

Home > Fact sheets by category > Healthy living > Pregnancy > Pregnancy problems > Diabetes - gestational.

Health information

Healthy eating

Healthy interactive

Directories

Diabetes - gestational

Gestational diabetes is diabetes that occurs during pregnancy. Diabetes is a common condition in which there is too much glucose in the blood. The pancreas either cannot make insulin or the insulin it does make is not enough and cannot work properly to control the amount of glucose in the blood.

Between three and eight per cent of pregnant women will develop gestational diabetes at week 24 to week 28 of pregnancy. Being diagnosed with gestational diabetes can be upsetting, but working closely with your doctor and health care team can help to lower your blood glucose levels and keep them within the normal range.

Symptoms
Diabetes often has no obvious symptoms. If symptoms occur, they can include:

Blurred vision
Unusual thirst
Excessive hunger
Excessive urination
Thrush infections
High blood pressure
Tiredness.

High risk groups
Certain women are at increased risk of developing gestational diabetes. High risk groups include:

Women over 30 years of age
Women with a family history of type 2 diabetes
Women who are overweight or obese
Indigenous Australians
Torres Strait Islanders
Women of particular ethnic groups including Indian, Chinese, Vietnamese, Middle Eastern, Polynesian and Melanesian women
Women with a history of gestational diabetes in a previous pregnancy.

How does gestational diabetes develop?
The placenta produces hormones that help the baby to grow and develop, but these hormones also block the action of the mother’s insulin. This is called insulin resistance.

As the pregnancy progresses, the mother’s energy needs increase. The body needs insulin so that glucose can get from the bloodstream into the cells where it can be used for energy. However, because a woman’s energy needs are higher during pregnancy, her insulin needs are also higher than normal.

When the pregnancy is over and the need for insulin returns to normal, the diabetes usually disappears.

Effects on the baby
Glucose crosses the placenta because it is required to meet the energy needs of the developing baby. If the mother’s blood glucose levels are raised, a greater amount of glucose crosses the placenta to the baby. To cope with the higher levels of glucose, the baby produces more insulin, which promotes excessive growth and fat.

If the mother’s blood glucose levels remain raised, the baby can be larger than normal and may need to be delivered early. Following delivery, a baby may experience low blood glucose, particularly if the mother’s blood glucose levels were elevated before birth. The mother’s condition can be monitored and treated. When gestational diabetes is well controlled, these risks are greatly reduced.

Diagnosis
Most women are diagnosed using a special test, which requires a blood sample to be taken after a sweet drink. These tests are usually performed when the woman is about six months pregnant. There are two types of tests:

Glucose challenge test (GCT) – blood is taken and the glucose level is measured one hour after the drink. If this is raised, an oral glucose tolerance test is then given.
Oral glucose tolerance test (OGTT) – involves taking a blood sample after the woman has fasted overnight and then a second blood sample two hours after she has a glucose drink. A diagnosis is based on the results of the OGTT.

Treatment
Treatment generally includes:

Diet – you are encouraged to eat a varied diet that is nutritionally appropriate for pregnancy, including foods rich in calcium, iron and folic acid. Your diet should be low in fat (particularly saturated fats) and high in fibre. Carbohydrates such as grains, cereals, fruits, pasta and rice should be eaten in moderation. It is essential to consult with a dietitian who can assess your nutritional intake and formulate a suitable meal plan.
Physical activity – regular safe physical activity like walking helps to keep you fit and prepares you for the birth of your baby. This will also help your insulin to control your blood glucose levels more effectively. However, always check with your doctor whether the type and amount of physical activity you choose is suitable.
Monitoring blood glucose levels – regular monitoring of your blood glucose levels is essential so that treatment can be assessed and changed as necessary. Insulin injections may be needed to help bring the glucose level into the normal range. Blood glucose lowering tablets are generally not used in pregnancy, although metformin may be prescribed for some women.

Long-term outlook
After the baby is born, the mother’s blood glucose levels usually return to the normal range. A follow-up OGTT is recommended six to eight weeks after the baby is born.

Research suggests that women who have gestational diabetes have a 50 per cent chance of developing type 2 diabetes within 20 years (or even higher in some groups). To reduce your risk, it is important to:

Maintain a healthy eating plan
Maintain a healthy weight for your height
Engage in regular physical activity
Have an OGTT at least every one to two years.

Where to get help

Your doctor
Obstetrician
Diabetes specialist or endocrinolgist
An accredited practising dietitian, contact the Dietitians Association of Australia
Diabetes Australia – Victoria Tel. 1300 136 588

Things to remember

Gestational diabetes is diabetes that occurs during pregnancy.
When the pregnancy is over, the diabetes usually disappears.
Women who develop gestational diabetes have a 30 to 50 per cent chance of developing type 2 diabetes within 20 years
A healthy lifestyle is important for both mother and baby to reduce risk of diabetes in the future.