Gestational diabetes: the facts

Illness in pregnancy ... Always see a doctor if you're concerned about any aspects of your health or wellbeing while ...
Illness in pregnancy ... Always see a doctor if you're concerned about any aspects of your health or wellbeing while pregnant. 

What is it?

Gestational diabetes is a pregnancy condition in which blood glucose levels rise beyond normal levels in women who aren’t diabetics, and who have never had elevated blood glucose levels prior to falling pregnant.

Diabetes Australia says that between 3-8 per cent of pregnant women will be diagnosed with gestational diabetes, usually between 24 to 28 weeks, or sometimes earlier.

Gestational diabetes occurs when the hormones that are produced to help the baby’s development actually create insulin resistance. The pancreas usually releases enough insulin to control how much glucose is in the blood, but in women with gestational diabetes, the pancreas isn’t efficient enough to prevent too much glucose from building up in the blood.

Although all women can develop gestational diabetes, some are more susceptible to it, including those who:

are 30 years old and older (particularly women over 35)
have a BMI of 30 or above
are of Aboriginal Australian, Asian or Middle Eastern ethnicity
have had gestational diabetes with earlier pregnancies
have prediabetes or glucose intolerance issues
have a family history of diabetes and/or gestational diabetes
have polycystic ovarian syndrome (PCOS) or other pregnancy complications in any previous pregnancies.

Women who have risk factors for gestational diabetes will have a test shortly after their pregnancy begins.

How is it diagnosed?
Gestational diabetes is diagnosed by an oral glucose test or a glucose challenge test. In the glucose challenge test, women drink a glucose solution then have the concentration of glucose in the blood tested. Women with gestational diabetes will then test high for glucose, as it won’t be broken down properly by the body.


The universal glucose challenge test is recommended for all pregnant women at 28 weeks, because it’s possible for completely healthy women to develop diabetes.

What are the symptoms?
In many cases there are no signs of the onset of gestational diabetes. Even in cases where women do experience symptoms, they may not be recognised as being indicative of diabetes, as they can mimic the normal side effects of pregnancy. These include:

extreme thirst
frequent urination
susceptibility to urinary tract infections and bladder infections
blurred vision.

What’s the treatment?
For many women with gestational diabetes, glucose levels can be controlled with a low GI diet and exercise. In some cases, oral medication or insulin may be needed as well.

Women with gestational diabetes will need to be tested throughout their pregnancies to check that their glucose levels are within a safe range. This can be done with a finger prick test, and possibly extra ultrasounds to monitor the size of the baby.

Does it affect the baby?
If gestational diabetes is left untreated, babies can grow very large as a result of the excess glucose crossing the placenta, leading to delivery complications and interventions, or, conversely, low birth weight. It can also put the baby at risk of having low blood sugar (hypoglycaemia) and jaundice.

Women with gestational diabetes have a higher chance of giving birth by caesarean. Their children are also at risk of obesity later in life.

Sufferers are also more inclined to develop pre-eclampsia, which can have severe consequences for the baby.

Other issues
Many women who are diagnosed with gestational diabetes during pregnancy won’t have it after their baby is born, but it’s possible for women and their babies (when they’re older) to develop Type 2 diabetes afterwards. As a result, women who had gestational diabetes need regular glucose tests to confirm that the condition has ceased, and that Type 2 diabetes doesn’t develop.

Facts verified by Dr Raewyn Teirney. Dr Teirney is gynaecologist, obstetrician and fertility specialist and a visiting medical officer at the Royal Hospital for Women in Sydney, and also consults from her private rooms at Maroubra and Kogarah.

For pregnancy support, check out the discussions in the Essential Baby forum. You can also join a group of women who are due at the same time as you.