fbpx

Gestational Diabetes

Pregnancy Questions

On this page, it’s all about gestational diabetes!

I have been working as a part of the Diabetes Clinic at The Royal Women’s Hospital for over 20 years, including many years as Head of Diabetes Clinic, an appointment I currently still hold. I have also conducted my own private obstetric practice, assisting thousands of women to manage their pregnancy and birth.

Over the last two decades there has been substantial research and education about the reasons gestational diabetes occurs, and the risks and ways to manage it. We have also seen an increase in the number of women with gestational diabetes.

Gestational diabetes is the fastest growing type of diabetes in Australia.

This page has been written to help provide you current information about GDM, tips to avoid diabetes in pregnancy and ways to manage diabetes if you are diagnosed during your pregnancy.

First of all, lets confirm: What is Gestational Diabetes Mellitus (GDM)?

Around 5-8% of pregnancies are affected by GDM.

When you have gestational diabetes, the average levels of glucose in your blood are higher on average, than they should be.

Your baby will then receive a higher level of sugar as it crosses the placenta.

This may have some adverse impact on the health of both you and your unborn baby if the condition is not diagnosed, monitored and managed.

What causes Gestational Diabetes?

There are a few risk factors to be aware of:

  • excessively rapid weight gain in pregnancy,
  • pre-existing obesity,
  • too much simple carbohydrate and processed food in the diet,
  • a family history of diabetes,
  • having a twin pregnancy,
  • advanced maternal age (often defined as over 35).
  • Past history of a big baby (over 4kg) in a previous pregnancy
  • or GDM previously may indicate a greater risk.
  • Some ethnic backgrounds are at greater risk including indigenous Australians, Polynesian and Maori, South East Asian and Middle Eastern.

The frequency of GDM is, unfortunately, rising rapidly in Western countries.

How is Gestational Diabetes diagnosed?

A test called a Glucose Tolerance Test (GTT) is routinely performed in all pregnancies at approximately 26 weeks. If any of the above risk factors are present the GTT should be performed earlier in your pregnancy. The test involves a fasting blood sugar test, then drinking a glucose solution, followed by two blood tests at one and two hours after the drink.

The test can be performed at any local pathology collection center, and requires a referral from your GP or specialist.

If the test shows I have GDM, what happens next?

You will be referred to a diabetic nurse educator who specialises in helping people manage all forms of diabetes. The nurse will instruct you in basic dietary principles to help reduce simple carbohydrate intake and equip you with a glucose monitor. Some simple regular exercise will be recommended. You can start testing your blood sugar levels at home and work, keeping a record to assess your progress.

What if diet and exercise alone aren’t enough?

If the average blood sugar levels remain high, then insulin will be prescribed and self-administered. This is because your body has reached its own maximum insulin production already. The administration is simple and easy thanks to modern insulin delivery systems.

How will my baby be monitored?

If you develop diabetes during your pregnancy, I will see you more frequently for the remainder of the pregnancy. A close eye is kept on the growth of your baby and the health of your placenta. Sometimes your baby can grow faster than is ideal, and on occasion, the function of the placenta can become impaired towards the end of pregnancy. If either of these happens, it may be safer to discuss and arrange delivery a week or two earlier than your due date.

For more information about managing diabetes in pregnancy please call for an appointment. 

Frequently Asked Questions about Gestational Diabetes

Will I need to inject myself with insulin if I have gestational diabetes?

This will depend on how your initial monitoring blood sugar levels look. Often with simple changes in diet and some regular exercise, the sugar levels can normalise. However, about 30-40% of women with GDM will need to commence Insulin to reduce their glucose levels to normal.

Will I have diabetes after my baby is born?

Almost always the answer is no. After the baby is born I advise patients to cease blood glucose monitoring, cease Insulin if it was commenced in pregnancy, and continue a healthy diet. At around 6- 8 weeks after delivery you should have another GTT to see if the condition is resolved.

Occasionally when we diagnose GDM in pregnancy, we are dealing with Type 2 diabetes which may have been pre-existing for a while, hence the importance of a follow up test.

Does having GDM mean I will need to have a caesarean section?

No, the diagnosis does not automatically mean you require a caesarean section. It is true that some women will grow very large babies associated with GDM. If this is the case a discussion around whether caesarean section is a good option will be had. For the most part with good management and baby being in the normal size range you can attempt a vaginal birth.

I’ve been diagnosed with GDM and now I don’t know what to eat.

Changing your diet is not always easy, but it’s important you look for changes you can make.

Firstly, avoid carbohydrates that will make your GDM worse, these are things like cakes, biscuits, sweet foods, sugary drinks and fruit juice.

Replace these foods with items that have a low GI – low glycaemic index. Try multigrain bread, legumes, kidney beans, vegetables, yoghurt and milk.

There are also lots of online recipes to provide ideas for you.

Try: Diabetes Recipes 

If I have GDM, how much more exercise should I be doing?

This depends on whether you were doing anything before the diagnosis. If you aren’t into regular exercise I would recommend walking every day, initially for 30 minutes, then build up to an hour. Other forms of suitable exercise include pilates, yoga and swimming.

Does having GDM mean my baby will be enormous at birth?

This is possibly the thing women fear most when GDM is diagnosed. Remember that some babies will be large simply because of genetics. Careful examination and ultrasound assessment in the third trimester help us predict an approximate birthweight. Most babies will be in the normal size range, but if blood sugar control is difficult, they do tend to have an increase in the fat layer.

If we do detect that your baby appears to be big during your pregnancy (often called macrosomia) a careful plan around birth will be formulated in consultation with you.

Glossary of terms for Gestational Diabetes

GDM – Gestational Diabetes Mellitus

GTT – Glucose Tolerance Test

Insulin – A protein hormone your pancreas gland produces, essential for metabolism of glucose.

Blood Glucose Level – The amount of glucose measured on testing of blood: measured in mm/l

Endocrine system – A group of glands in your body responsible for producing hormones. These include the thyroid, adrenal, pituitary, gonadal ( ovaries and testes) and many others.

Fasting blood glucose – Blood sugar level taken before breakfast, after nothing to eat or drink from midnight

Glucagon – A protein hormone your liver produces that increases your blood glucose level

Glucose – The most basic form of sugar, and prime energy source for cell metabolism

Hyperglycaemia – An excessively high reading of blood sugar level. In pregnancy fasting over 5 mm/l, and post meal levels over 6.7mm/l are considered elevated 


Diabetes is a complex condition, you may have many questions about how to manage your pregnancy and diabetes.

Send us an email to make an appointment or call the rooms during business hours.