Gestational diabetes is diabetes that occurs during pregnancy. Diabetes is a common condition where there is too much glucose in the blood. Women usually recover from gestational diabetes after their baby is born, when their blood glucose levels return to normal.
Our body makes insulin to help keep our blood glucose at the right level. Blood glucose becomes higher when we can’t make enough insulin or when it does not work as well as it should
Development of gestational diabetes
During pregnancy, hormones are made by the placenta to help the baby develop and grow. These hormones, however, stop the mother’s insulin from working properly. This is called insulin resistance. As the pregnancy develops and the baby grows bigger, the mother’s body has to make more insulin to keep her blood glucose at normal levels.
Later in pregnancy the amount of insulin needed to keep blood glucose levels normal is two to three times higher than usual. If the body is unable to produce enough insulin to keep blood glucose levels in the normal range, gestational diabetes develops.
Women at risk of gestational diabetes
Between three and eight per cent of pregnant women develop gestational diabetes. It is usually detected around weeks 24 to 28 of pregnancy, although it can develop earlier. Being diagnosed with gestational diabetes can be both unexpected and upsetting.
Certain women are at increased risk of developing gestational diabetes. This includes women who:
- are over 30 years of age
- have a family history of type 2 diabetes
- are overweight or obese
- are of Aboriginal and Torres Strait Islander descent
- are of particular cultural groups, such as Indian, Chinese, Vietnamese, Middle Eastern, Polynesian and Melanesian
- have previously had gestational diabetes
- take some antipsychotic or steroid medications
- have previously had a baby whose birth weight was greater than 4,500 grams (4.5 kg)
- have had a previous complicated pregnancy.
- have had polycystic ovarian syndrome.
Some women who develop gestational diabetes have no known risk factors.
Symptoms of gestational diabetes
Gestational diabetes usually has no obvious symptoms. If symptoms do occur, they can include:
- unusual thirst
- excessive urination
- thrush (yeast infections).
Diagnosis of gestational diabetes
Most women are diagnosed using a pathology test, which requires a blood sample to be taken before and after a glucose drink. These tests are usually performed between 24 and 28 weeks into the pregnancy, or earlier if you are at high risk.
To diagnose gestational diabetes a pregnancy oral glucose tolerance test (POGTT) is recommended.
This involves taking a blood test after fasting overnight. Next you have a drink containing 75 grams of glucose and blood is taken to be tested one and two hours afterwards.
Diagnosis of gestational diabetes is made if the fasting blood glucose is raised or the two-hour blood glucose is raised (or both).The new diagnostic guidelines for gestational diabetes state a raised blood glucose level at one hour after the glucose drink also indicates gestational diabetes.
Some health centres may be still using the Glucose Challenge Test (GCT). A sweet glucose drink is given and the blood glucose measured one hour after the drink. If this is above normal, an oral glucose tolerance test is required. This test is no longer considered part of diagnostic testing as it is not specific or sensitive enough for diagnosing GDM.
Treatment for gestational diabetes
If you are diagnosed with gestational diabetes it is important that you are supported and know what to do to manage it. Health professionals such as your doctor, a dietitian, a diabetes nurse educator or sometimes a diabetes specialist will help you understand what to do and will support you. Family also can be a great support and it is important that they also understand about gestational diabetes and how it is managed.
It is important that blood glucose is kept as close to normal as possible, especially during pregnancy. High blood glucose levels can affect the baby before birth, later as a child and even as an adult.
During pregnancy, glucose crosses the placenta from mother to baby to provide energy for the growing baby. If your blood glucose levels are higher than normal, extra glucose will cross the placenta to the baby. To deal with this extra glucose, the baby then makes more insulin which makes the baby grow larger more quickly. If your blood glucose levels remain high, the baby may become larger than normal. This can lead to problems during and after birth.
Keeping blood glucose in the recommended range can prevent problems during birth and also helps reduce the baby’s risk of being overweight in childhood and developing type 2 diabetes later in life.
Management of gestational diabetes
Advice to help manage gestational diabetes (which will help to keep blood glucose levels close to normal) may include:
- healthy diet – make sure you are eating a nutritious diet that helps you maintain a healthy weight. Choose varied and enjoyable food, including foods rich in calcium (milk and cheese), iron (red meat, chicken and fish) and folic acid (dark green leafy vegetables). Include some carbohydrates at each meal such as grains, cereals, fruits, pasta and rice. Reduce your saturated fat intake by limiting the amount of processed and takeaway foods that you eat. Avoid foods and drinks containing a lot of added sugar. Discuss with a dietitian how much carbohydrate you should eat and the best way to spread it out throughout the day to help control your blood glucose levels. A dietitian can also help you with any other questions about how to make sure you are eating the best diet for you and your baby
- physical activity – such as walking, helps to keep you fit, prepares you for the birth of your baby and will help to control your blood glucose levels. Check with your doctor before starting a new or particularly strenuous exercise regimen
- monitoring your blood glucose levels – is essential. It gives a guide as to whether the changes you have made to your lifestyle are effective or whether further treatment is required. A diabetes nurse educator can teach you how and when to measure your blood glucose levels. They will discuss the recommended blood glucose levels to aim for. Your doctor or diabetes educator can help you link in with the National Diabetes Services Scheme (NDSS) for cheaper blood glucose strips. Regular contact with your diabetes educator or doctor is recommended
- insulin injections – may be needed to help keep your blood glucose level in the normal range. Many diabetes tablets are not safe to take during pregnancy so insulin injections may be necessary. Insulin is safe to take during pregnancy and does not cross the placenta from the mother to the baby
- education – it is very important that you get information and support from your diabetes educator or doctor on how insulin works, how to give insulin and how to store it. Insulin sometimes causes blood glucose levels to go too low (hypoglycaemia), therefore it is very important that you learn the signs and symptoms of this and how to prevent and treat it (as well as safe blood glucose levels for driving).
After your baby is born
If you have been having insulin injections to help manage gestational diabetes, you can usually stop these injections once your baby is born. This is because your blood glucose levels usually return to normal quite quickly after the baby’s birth.
Your blood glucose levels will be measured for a few days after your baby is born to make sure that they are within the normal range. Testing times are usually before breakfast and two hours after meals. An Oral Glucose Tolerance test (OGTT) is done six to eight weeks after the baby is born to make sure that diabetes has gone away.
Following the birth of your baby, it is important that your baby’s blood glucose levels are measured to make sure that their blood glucose is not too low. If it is, this can be treated by feeding your baby breast milk or formula. Breastfeeding is encouraged as this is best for you and your baby.
A baby whose mother had gestational diabetes will not be born with diabetes, but, they may be at risk of developing type 2 diabetes later in life.
Future pregnancies and gestational diabetes
If you have had gestational diabetes you are more likely to have it again in future pregnancies. For that reason an OGTT will be performed early in any future pregnancy to look for gestational diabetes. If this test is normal, then another OGTT will be done again later in the pregnancy (between 22 and 28 weeks) to make sure blood glucose levels are still normal.
Reducing your risk of type 2 diabetes
Women who have gestational diabetes have a high chance (almost one in two) of developing type 2 diabetes within 10 to 20 years. Type 2 diabetes can be prevented, so it is important to take steps to reduce your risk.
- maintain a healthy eating plan
- maintain a healthy weight for your height
- do regular physical activity
- have a follow-up blood test (OGTT) every year to check your blood glucose levels.
Where to get help
- Your doctor
- Diabetes specialist or endocrinologist
- Diabetes educator – ask at the hospital where you are booked to have your baby, or alternatively, you may see a diabetes educator privately
- Diabetes Info Line Tel. 1300 136 588
- Dietitians Association of Australia Tel. (02) 6163 5200
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.
- A healthy lifestyle is important for both mother and baby to reduce their risk of diabetes in the future.
- If you have had gestational diabetes before, in future pregnancies, a test will be performed early in the pregnancy to make check that your blood glucose levels are in the normal range .
This page has been produced in consultation with and approved by:
Diabetes Australia Victoria
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