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Pregnancy is an exciting and turbulent time, full of new experiences and things to look forward to. During pregnancy you do everything you can to look after your own health, knowing that your baby’s good health depends on it.

Gestational diabetes is a disease that occurs only during pregnancy. It can threaten the well-being of you and your baby, both while you are pregnant and after your baby is born. Unfortunately, gestational diabetes rarely exhibits any symptoms and it is therefore crucial that you are aware of the high risk factors for the condition, and that you are screened for the disease.

Read below to find out more about gestational diabetes.

What is gestational diabetes?

Gestational diabetes is a temporary form of diabetes which begins during pregnancy and usually disappears after delivery. It affects between 3 to 8 percent of pregnant Australian women.

As with diabetes, gestational diabetes means that the body is not able to make and use enough insulin. In gestational diabetes the insulin is blocked from doing its job – this is called insulin resistance. Without enough insulin, glucose cannot move from the blood to the body’s cells where it is converted to energy. Instead, it remains in the blood where it builds up to high levels. This is called hyperglycemia.

Insulin resistance in women with gestational diabetes is actually caused by hormones in the placenta interfering with insulin. The function of the placenta in pregnancy is to supply the growing baby with nutrients and water from the mother’s circulation. In this process, the placenta produces a number of hormones which have a critical role in maintaining the pregnancy. Unfortunately, some hormones produced in the placenta, such as estrogen, cortisol, and human placental lactogen (HPL), have the effect of blocking insulin. This usually begins in weeks 24-28 of pregnancy and worsens as the pregnancy develops and the placenta becomes larger.

Any woman can develop gestational diabetes during pregnancy, though there are a number of high risk factors. These include:

  • Obesity
  • A family history of Type 2 diabetes
  • Previous difficulties carrying a pregnancy to term
  • Being older than 30 years of age
  • Being of Indigenous Australian or Torres Strait Islander nationality
  • Having gestational diabetes during previous pregnancies
  • Being of certain ethnic ancestory, including Indian, Chinese, Polynesian/Melanesian, Vietnamese or Middle Eastern

Testing for gestational diabetes

Testing for gestational diabetes is usually carried out between 24 to 28 weeks into the pregnancy, although those with high risk factors may be tested earlier.

The most common screening test for gestational diabetes is the Glucose Challenge Test (GCT), where blood is taken for a glucose measurement one hour after a glucose drink. If this test is abnormal, an Oral Glucose Tolerance Test (OGTT) is done. For an OGTT a blood sample is taken before and two hours after a glucose drink.

Current research: Research published in the February 2004 issue of Diabetes Caresuggests that measuring the size of the unborn baby may provide a more accurate indication of gestational diabetes than testing the mother’s blood glucose levels. Using ultrasound technology, researchers found that giving insulin only to mothers whose baby’s abdominal size was in the 75th percentile or higher produced better results than giving it to all mothers whose blood glucose levels were higher than normal.

Is gestational diabetes harmful?

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If gestational diabetes is managed well and blood sugars are kept under control, no harm should come to you or your baby. Because gestational diabetes usually occurs in late pregnancy the baby’s development is not affected. However, untreated or poorly controlled gestational diabetes can cause the following complications:

Macrosomia. Gestational diabetes can result in a larger than normal baby. The baby receives all of its food and nutrients from the mother’s blood. If the mother’s blood has too much glucose, the baby’s pancreas will sense this and produce extra insulin in an attempt to get rid of the extra glucose. Because the baby is getting more energy than it needs, the extra energy is stored as fat.

Delivery problems. Babies with macrosomia can incur damage to the bones and nerves of their arms and shoulders during delivery. Sometimes a caesarian section may be necessary to deliver the baby if it is too large.

Low blood sugar levels. Gestational diabetes can increase the newborn’s risk of developing low blood glucose levels. After the birth, the baby continues to produce a high level of insulin, but without receiving the high levels of glucose from its mother, thereby causing blood sugar levels to drop. The baby’s blood sugar levels should be checked shortly after birth and rectified intravenously if necessary.

Obesity and Type 2 diabetes. Babies with excess insulin become children who are at risk for obesity and adults who are at risk for Type 2 diabetes, both of which lead to other serious health problems.

Jaundice. Untreated gestational diabetes can also result in jaundice for the newborn. Jaundice is a build-up of old red blood cells that the body can’t process fast enough. This problem goes away with treatment.

Treating and managing gestational diabetes

The most important goal in treating gestational diabetes is to control blood glucose levels. This can usually be achieved effectively through:

  • Special meal plans
  • Regular exercise
  • Regular blood glucose testing

A doctor or dietitian can recommend a specialised meal plan that takes into account your weight, stage of pregnancy, food preferences, level of exercise, and any other relevant factors. You should also ask your doctor to help you design a balanced exercise program. The more regularly you exercise, the better your control of blood glucose levels should be. Be careful when you exercise though; make sure that your pulse is not too high and the exercise not too strenuous. If you experience any unusual pain during exercise you should call your doctor immediately.

You can use a food and exercise diary to log your foods and activities. Try Allan Borushek’s Pocket Food and Exercise Diary or an electronic diary, such as the CalorieKing Food and Exercise Diary (available at, or via software for Windows, Mac or Palm OS.) If exercise and diet are not effective in stabilising blood glucose levels, you may require insulin injections. Your doctor will advise you on this.

Blood glucose testing is important to see how well you are controlling your levels. Testing can be done at the doctor’s office or at home. Your doctor or diabetes educator may be able to provide you with a user-friendly blood glucose monitoring machine and teach you how to read your blood glucose and food intake profiles. You can record and monitor your results using the CalorieKing Diabetes Log.

Post-natal concerns

Gestational diabetes usually goes away after pregnancy. However, if you have had gestational diabetes, you face an increased risk of developing Type 2 diabetes later in life, with a 30 to 50 percent chance of developing it within 15 years after pregnancy. You also have an increased chance of gestational diabetes occurring in a future pregnancy. These risks are increased if you are overweight. To help lower the risk of future diabetes, take steps to maintain a healthy lifestyle.

  • Maintain a healthy weight and aim to minimise extra fat – especially around the waist.
  • Make wise food choices.
  • Exercise regularly and with variety.
  • Before considering another pregnancy, get your doctor or diabetes educator to monitor your blood sugar levels.

References :

This article was compiled in consultation with Calorie King experts and in reference to the following sources:

Diabetes Australia, ‘Gestational Diabetes’,

National Institute of Child Health and Human Development, ‘Are You at Risk for Gestational Diabetes?’

Tori Kordella, ‘Gestational Diabetes: Are Prediction and Prevention Possible?’ Diabetes Forecast, January 2004

Calorie King
CalorieKing's mission is to provide the best information, tools and education to Australians to help them conquer their weight.

CalorieKing is the brainchild of Allan Borushek, registered dietitian, co-found here at and author of "Allan Borushek's Pocket Calorie & Fat Counter", Australia's best-selling calorie counter for over 30 years.

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