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10 February, 2010

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Diabetes - gestational

Gestational diabetes is diabetes that occurs during pregnancy. Symptoms may include excessive thirst, urination, fatigue or thrush infections. However symptoms are often not obvious in gestational diabetes.

When the pregnancy is over, gestational diabetes usually disappears. However women are at a greater risk of developing type 2 diabetes after experiencing gestational diabetes.

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 cannot control the level of glucose in the blood.

Gestational diabetes is usually detected around the 24th to 28th week of pregnancy, although it can develop earlier. Up to eight per cent of pregnant women will develop gestational diabetes.

Risks to the mother and baby are greatly reduced when gestational diabetes is well controlled. Working closely with a doctor and health care team, including a dietitian, can help lower a woman’s blood glucose levels and keep them within a normal range.

High risk groups
Some 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 and Torres Strait Islanders
Women of some 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 impair the action of the mother’s insulin. This is called insulin resistance. As the pregnancy progresses, the mother’s energy needs increase and her insulin needs are also higher than normal. Some women are unable to produce extra insulin and blood glucose levels rise.

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 from mother to baby to meet the energy needs of the developing baby. If the mother’s blood glucose levels are raised, a greater amount of glucose will cross the placenta to the baby.

To cope with this extra glucose the baby produces more insulin, which promotes excessive growth and fat in the baby.

If the mother’s blood glucose levels remain raised, the baby can be larger than normal at birth. Following delivery, the baby may experience low blood glucose, particularly if the mother’s blood glucose levels were elevated before the birth. The baby will not be born with diabetes.

These risks are greatly reduced if gestational diabetes is well-controlled.

Symptoms
Gestational diabetes usually has no obvious symptoms. If symptoms occur, they can include:

Unusual thirst
Excessive urination
Tiredness
Thrush infections.

Diagnosis
Two types of tests are used to diagnose gestational diabetes. These tests are usually performed at about the 24th week of pregnancy and require a blood test after consuming a glucose drink.

Glucose challenge test (GCT) – in this first test, glucose levels are measured by blood test one hour after a glucose drink. If results from this test are abnormal, an oral glucose tolerance test is required.
Oral glucose tolerance test (OGTT) – this test requires an overnight fast by the pregnant woman. A blood sample is then taken before, and two hours after, consuming a glucose drink.

Treatment
Gestational diabetes is managed with:

Diet – pregnant women are encouraged to eat a varied diet including foods rich in calcium, iron and folic acid, low in saturated fats and high in fibre. Carbohydrates such as grains, cereals, fruits, pasta and rice are important to provide energy and essential nutrients.
Physical activity – regular physical activity like walking helps control blood glucose levels and improve fitness.
Monitoring blood glucose levels – regular testing of blood glucose levels is essential so that treatment can be assessed and changed as necessary.
Insulin injections - may be needed to help control glucose levels. Blood glucose lowering tablets are generally not used in pregnancy. Insulin is safe to take during pregnancy and does not cross the placenta from the mother into the baby.

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

Women who have gestational diabetes have a higher chance of developing type 2 diabetes within 20 years. Steps to reduce the risk of type 2 diabetes include:
Maintain a healthy eating plan
Maintain a healthy weight
Engage in regular physical activity
Have an annual oral glucose tolerance test.

Where to get help

Your doctor
Obstetrician
Diabetes specialist or endocrinologist
An accredited practising dietitian - contact Dietitians Association of Australia
Diabetes Australia – Vic 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 an increased risk of developing type 2 diabetes

You might also be interested in:
Diabetes.
Diabetes - diagnostic tests.
Diabetes and healthy eating.
Diabetes and kidney failure.

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