What is gestational diabetes?
Gestational diabetes mellitus is a type of diabetes you can have when pregnant. It is often called GDM for short.
Gestational diabetes will normally be diagnosed with a blood test and an oral glucose tolerance test (OGTT) when you are between 24 and 28 weeks pregnant. You will have a blood test before the glucose drink and then two more blood tests after the drink. Your doctor may get you to do this test earlier in your pregnancy if you have symptoms or risk factors for gestational diabetes.
If you’re diagnosed with gestational diabetes don’t panic. You haven’t done anything wrong and you are not alone.
About one in every seven Australian women have gestational diabetes during pregnancy. It can generally be managed with diet and exercise, although some women may need to take tablets or insulin injections too.
Gestational diabetes usually goes away after the baby is born. Having gestational diabetes increases your risk of developing type 2 diabetes later in life.
Why does gestational diabetes happen?
When you are pregnant, the placenta produces special pregnancy hormones. These hormones can make the insulin in your body work less effectively than it normally does which causes high blood glucose levels. If you have a lot of glucose in your blood, it can pass through the placenta to your baby and make them grow too big. This is known as macrosomia.
As well as this, your body might not be able to make enough insulin to meet the extra amount that you need in pregnancy.
What risk factors are associated with gestational diabetes?
Factors that may increase your risk of developing GDM during pregnancy include:
- Ethnicity: Asian, Indian subcontinent, Aboriginal, Torres Strait Islander, Pacific Islander, Maori, Middle Eastern, non-white African Diabetes in Pregnancy Multicultural Resources
- Pre-pregnancy body mass index (BMI) >30 kg/m²
- Previous hyperglycaemia in pregnancy
- Previous elevated blood glucose level
- Maternal age ≥40 years
- Family history of diabetes (close relatives with diabetes or a sister with hyperglycaemia in pregnancy)
- Previous macrosomia (baby with birth weight >4500g or >90th percentile)
- Polycystic ovary syndrome
- Medications: corticosteroids, antipsychotics
When will I be tested?
All women are tested for gestational diabetes in the 24th to 28th week of pregnancy. This is because symptoms are not obvious. If you are you are classed as being at higher risk you may have the test earlier.
How is gestational diabetes diagnosed?
Gestational diabetes is diagnosed with a blood test and an oral glucose tolerance test (OGTT). The test requires you to fast for 8-10 hours (generally overnight, missing breakfast). Once you arrive at the clinic you will be given a blood test, followed by a sweet drink containing glucose. An hour later your blood is tested again. You are not allowed to have anything to eat or drink, except water, during this time. A third and final blood test an hour after the second test. The test is looking to see how well your body has used glucose over that period of time.
Some clinics give you the results later that day, but others may take up to 48 hours.
How is gestational diabetes managed?
If you are diagnosed with gestational diabetes there are things you need to do to manage it. A healthy diet, regular exercise, checking your blood glucose levels and taking tablets or insulin all help to manage gestational diabetes by keeping your blood glucose levels in a healthy range. This will reduce the risks to you and the baby.
Will gestational diabetes harm the baby?
Untreated gestational diabetes can cause problems for you and your baby. Women with gestational diabetes are more likely to have a caesarean section, pre-term labour and birth, and induced labour than women without gestational diabetes.
Treating gestational diabetes by keeping blood sugar levels as close to the targets recommended by your GP and healthcare team will reduce the risk of any complications. They will also keep a close eye on your baby and how it grows to prevent any complications from happening.
Don’t panic. Keep the risks in perspective
While there are risks associated with gestational diabetes it is important to remember that every pregnancy has risks, regardless of whether the mother has gestational diabetes. Of course, you want a perfect pregnancy and it’s natural to be worried. Look at your diagnosis as the first step towards reducing any chances of complications. Your healthcare team will be able to guide and support you throughout the rest of your pregnancy to significantly lessen any risks. Read Crystal’s personal story and experience with gestational diabetes.