Between three and eight per cent of women will get gestational diabetes between the 24th and the 28th week of pregnancy, sometimes earlier. It usually goes away after the baby is born.
Women who are more likely to get gestational diabetes are:
- older mothers
- women who have a family history of type 2 diabetes
- women who are overweight
- women who are from certain ethnic backgrounds, including South Asian, Vietnamese, Chinese, Middle Eastern and Polynesian/Melanesian.
Other women at risk include those who have had gestational diabetes, polycystic ovarian syndrome, large babies or birth complications in the past
What is gestational diabetes?
The hormone insulin moves glucose or sugar from your blood and into your body’s cells, where it is used for energy. When you have diabetes, this process is blocked and your cells become 'insulin resistant'. This causes you to have too much glucose in your blood. In pregnancy, the hormones from the placenta, which help your baby to grow, can cause your cells to become insulin resistant. Usually in pregnancy the body produces more insulin to counter this. In some women, however, this doesn’t happen and they develop gestational diabetes.
There are many health issues associated with gestational diabetes, including that both the mother and baby will have an increased risk of developing type 2 diabetes later in life. During the pregnancy, gestational diabetes can lead to excessive sugars and fats crossing the placenta, which can have an effect on the baby’s growth, usually making them bigger. Giving birth to larger babies can also lead to problems with the birth. Sometimes, even though it might not seem to make sense, some babies (particularly larger babies) are born with blood sugar levels that are too low – this is called hypoglycaemia.
Testing for gestational diabetes
During pregnancy, women are generally offered a test to screen for glucose (called a Glucose Challenge Test). The screening test can identify women who may have elevated blood sugars. If you have elevated blood sugar levels you will be offered a Glucose Tolerance Test (GTT). The GTT assesses how your body responds to a 'glucose load' or how efficiently the glucose is moved from your blood to your body's cells. You are required to fast for 8 to 12 hours and then you have a blood test. After the blood test you have a drink that contains glucose. One or two hours after you have the drink another blood test is done. Gestational diabetes will be diagnosed if your blood sugar levels are above what they should be.
Managing gestational diabetes
Gestational diabetes can be managed with healthy eating, physical activity, monitoring your blood glucose levels and sometimes medication.
A good diet can keep your blood sugar levels within target. With diabetes you are encouraged to eat regular meals, eat small amounts often, and include some carbohydrate in every meal or snack.
Your diet should be enjoyable and varied, low in saturated fats and high in fibre. Avoid carbohydrates that have little nutritional value like cakes, biscuits, juices and soft drinks. Choose more complex carbohydrates such as multigrain breads and breakfast cereals, rice (preferably Doongara or Basmati as they have a lower glycaemic index), pasta and noodles. Legumes such as baked beans, red kidney beans and lentils and fruit, milk and yoghurt are also good choices.
See the section on healthy pregnancy for more information about diet and exercise.
If you have gestational diabetes, you will need to learn how to measure your blood sugar levels. Fifty per cent of women who develop gestational diabetes ultimately develop type 2 diabetes. If you are diagnosed with gestational diabetes, it is very important that you have regular follow-up tests for diabetes after the pregnancy or before becoming pregnant again.
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