Gestational diabetes

Gestational diabetes mellitus (GDM) is a form of diabetes that occurs during pregnancy and usually goes away after the baby is born.

Gestational diabetes occurs when the hormones produced by the placenta make it hard for your body to use insulin properly. This is called insulin resistance. Some women can’t produce enough extra insulin to overcome this. Glucose levels start to rise in your blood leading to diabetes.

Gestational diabetes is usually diagnosed from a blood test 24 to 28 weeks into pregnancy. If you have risk factors for gestational diabetes you may be tested earlier in your pregnancy.

Risk factors for gestational diabetes include:

  • Gestational diabetes in a previous pregnancy
  • Being older, for example over 40 years
  • Aboriginal or Torres Strait Islander background
  • Melanesian, Polynesian, Indian subcontinent, Middle Eastern or Asian background
  • Polycystic ovary syndrome
  • Family history of diabetes (parent or sibling)
  • Large baby (4,500g or more) in previous pregnancy
  • Overweight or recent weight gain

Finding out you have gestational diabetes can be a shock and cause you to worry about your pregnancy and your baby. Getting the right information and support will help. Talk to your healthcare team.

Most women with gestational diabetes will have a healthy pregnancy and baby.


The goal of gestational diabetes management is to keep blood glucose levels within a healthy range.

If blood glucose levels are high during pregnancy, the extra glucose passes through the placenta to the baby. The baby will then make extra insulin, which can cause the baby to grow too big. A large baby can lead to difficulties with labour and birth.

You can manage gestational diabetes by:

Most women will no longer have diabetes after the birth. However, having gestational diabetes does increase your risk of developing type 2 diabetes later on. It is very important to check for diabetes 6-12 weeks after birth, or as soon as you can after this time.

Daily life

When you are diagnosed with gestational diabetes you will be referred to a diabetes team. This may include:

  • An endocrinologist (medical specialist in diabetes)
  • A credentialled diabetes educator (a nurse or other allied health professional who has specialised in diabetes management)
  • An accredited practicing dietitian

You will be registered on the National Diabetes Services Scheme (NDSS) National Gestational Diabetes Register for 12 months. This will allow you to access subsidised diabetes supplies at your community pharmacy. The NDSS also provides reliable information about gestational diabetes.

The goal of managing gestational diabetes is to keep your blood glucose levels within a target range. You can do this by:

  • Eating well – your diabetes team will help you work out an eating plan based on your preferences and tolerances.
  • Monitoring your blood glucose levels (BGLs) – your diabetes educator will usually supply you with a glucose meter and shown how to use it. You can also purchase a glucose meter from your community pharmacy. Usually, you will be checking your BGLs four times a day: when you wake up and one to two hours after each meal.
  • Staying active – this does not mean you need to join the gym. Regular walks, moving around the house or garden will all help. Other options include swimming, yoga, pilates or gentle strengthening exercises. Choose something you enjoy. Aim for 30 minutes a day, 5 days a week. If you’re unsure, speak to your doctor.
  • Taking medication (metformin) or insulin – for some women, medication or insulin may be necessary to keep your blood glucose levels in target. Needing insulin is not your fault and will not harm your baby. Your diabetes educator will show you how to inject insulin.

Your pregnancy healthcare team (your GP, midwife, obstetrician) will continue to monitor you and your baby throughout your pregnancy.


Can gestational diabetes affect my baby?

If your gestational diabetes is not managed well and your blood sugar levels stay high, your baby may grow too large or be at an increased risk of miscarriage or stillbirth. A large baby increases the risk of injury during birth as well as caesarian delivery, forceps delivery and the risk that the baby may need special care following the birth. In the long-term, babies born to mothers with gestational diabetes are at an increased risk of obesity and type 2 diabetes later in life.

How will gestational diabetes affect me?

Having gestational diabetes may make your pregnancy a little more challenging. You will need to monitor your blood sugar levels regularly as well as eat well and be physically active. This might mean making small changes to the way you do things, such as grocery shopping, cooking or moving.

All this might make you feel anxious, and that’s normal and perfectly understandable. Pregnancy can be stressful enough without a diagnosis of gestational diabetes too. There are several health professionals who can help you, including your GP, specialist doctor, diabetes educator or dietitian. If you are feeling overwhelmed or feel you need help, talk to your GP to get the support you need.

The upside is, that eating well and being physically active during your pregnancy will help you and your baby to have a healthy, uncomplicated pregnancy and birth. In many cases, women choose to continue the healthy lifestyle changes made after their pregnancy because they feel so much better for it.

In the longer-term, having gestational diabetes increases your risk of developing type 2 diabetes. In fact, 50% of women who have had gestational diabetes develop type 2 diabetes within 10-20 years. However, type 2 diabetes can be prevented or delayed through healthy eating, regular physical activity and weight loss and living well during your pregnancy is the start of that. It is recommended that you see your doctor every 1-3 years to be tested for type 2 diabetes.

Will I have to inject myself with insulin to manage my gestational diabetes?

Most women with gestational diabetes can keep their blood glucose levels within the recommended range by monitoring their blood sugar levels, eating well and staying physically active. However, 10-20% of women need to take tablets (metformin) or inject insulin during their pregnancy as well. Your diabetes educator will show you how to inject correctly and safely and record your blood sugar levels.

Will insulin or metformin harm my baby?

No. Both metformin and insulin are safe for your baby.

Can I breastfeed if I have gestational diabetes?

Breastfeeding is recommended for all women, including women with gestational diabetes. Breastfeeding provides the best start for your baby and can help you to return to your pre-pregnancy weight.

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