Gestational diabetes is a type of diabetes that develops during pregnancy. It occurs when blood glucose levels become higher than normal because the body cannot produce or use insulin effectively enough to meet the increased demands of pregnancy.

It most commonly develops during the second or third trimester and is usually detected through routine pregnancy testing.

For most women, blood glucose levels return to normal after the baby is born. However, having gestational diabetes increases the risk of developing type 2 diabetes later in life.

For more general information, see our Diabetes guide.

What Causes Gestational Diabetes?

During pregnancy, the placenta produces hormones that help your baby grow and develop.

Some of these hormones reduce the effectiveness of insulin, a hormone that helps move glucose from the bloodstream into the body’s cells for energy. This is known as insulin resistance.

As pregnancy progresses, the body usually produces more insulin to compensate. However, gestational diabetes can develop when the pancreas cannot produce enough extra insulin to keep blood glucose levels within the recommended range.

You can learn more about pregnancy and common pregnancy-related health conditions in our Pregnancy guide.

Who Is at Risk?

Gestational diabetes can affect anyone during pregnancy, but some people have a higher risk.

Risk factors can include:

• having had gestational diabetes during a previous pregnancy
• being over 35 years of age
• having a family history of type 2 diabetes
• being above a healthy weight before pregnancy
• gaining more weight than recommended during pregnancy
• having polycystic ovary syndrome (PCOS)
• previously giving birth to a large baby
• taking certain medicines, including some corticosteroids or antipsychotic medicines
• belonging to some population groups with a higher risk of diabetes

Having one or more risk factors does not necessarily mean you will develop the condition.

Symptoms of Gestational Diabetes

Most people with gestational diabetes do not experience noticeable symptoms. Therefore, routine screening during pregnancy is important.

When symptoms do occur, they may include:

• increased thirst
• urinating more frequently than usual
• tiredness or fatigue
• blurred vision
• recurrent infections

However, many of these symptoms can also occur during a normal pregnancy. Testing is the most reliable way to diagnose the condition.

How Is Gestational Diabetes Diagnosed?

Doctors usually diagnose gestational diabetes using an oral glucose tolerance test, commonly called an OGTT.

Testing is commonly performed between 24 and 28 weeks of pregnancy. However, people at higher risk may be tested earlier.

An OGTT usually involves:

• fasting beforehand as instructed
• having a fasting blood test
• drinking a glucose-containing drink
• having additional blood tests after the drink to measure how your body processes glucose

Your doctor or maternity healthcare team will explain how to prepare for the test and what your results mean.

For more information, see Pregnancy, Birth and Baby’s pregnancy diabetes information.

Can Gestational Diabetes Affect Your Baby?

Most women with gestational diabetes can have a healthy pregnancy and baby when the condition is carefully managed.

However, uncontrolled high blood glucose can increase the risk of pregnancy and birth complications.

These may include:

• a baby growing larger than expected
• complications during labour and delivery
• increased likelihood of caesarean birth
• premature birth
• low blood glucose in the baby after birth
• high blood pressure during pregnancy
• pre-eclampsia

Good blood glucose management can significantly reduce these risks.

You can also find further information from Diabetes Australia about diabetes during pregnancy.

How Is Gestational Diabetes Managed?

Treatment aims to keep blood glucose within the range recommended by your healthcare team while supporting a healthy pregnancy.

Management may involve several approaches.

Healthy Eating

A healthy, balanced diet can help manage blood glucose while providing the nutrients needed during pregnancy.

Your healthcare team may refer you to a dietitian who can help you develop an eating plan suited to pregnancy and your individual glucose levels.

Rather than removing entire food groups or severely restricting carbohydrates, the focus is generally on appropriate portions, food choices and regular meals.

Physical Activity

Regular physical activity can help the body use insulin more effectively and lower blood glucose.

Activities such as walking may be suitable during pregnancy, depending on your individual circumstances.

Always follow your doctor or maternity healthcare professional’s advice about exercise during pregnancy.

Monitoring Blood Glucose

You may need to check your blood glucose levels regularly at home.

This usually involves using a blood glucose meter to test a small drop of blood from your finger.

Keeping a record of your results can help your healthcare team understand whether your treatment plan is working effectively.

Your MediAdvice pharmacist or diabetes educator can also explain how to use blood glucose monitoring equipment correctly.

Medication and Insulin

Some people can manage their glucose levels through changes to diet and physical activity alone.

However, others may require medication or insulin.

Your doctor will determine whether treatment is required and which option is appropriate during pregnancy.

Do not start, stop or change diabetes medicines without discussing this with your healthcare professional.

What Happens After Your Baby Is Born?

For most women, blood glucose levels return to normal after delivery.

However, your healthcare team will usually recommend follow-up testing to confirm that your glucose levels have returned to an appropriate range.

Having gestational diabetes also increases your future risk of developing type 2 diabetes.

Therefore, maintaining healthy lifestyle habits and completing recommended diabetes screening can help identify future changes in blood glucose early.

Our Diabetes guide provides more information about type 1 and type 2 diabetes.

Can Gestational Diabetes Be Prevented?

It is not always possible to prevent the condition.

Some risk factors, such as family history and age, cannot be changed.

However, entering pregnancy at a healthy weight where possible, eating a balanced diet and remaining physically active may help reduce the risk.

If you are already pregnant, do not attempt to lose weight unless specifically advised by your healthcare professional. Instead, discuss healthy pregnancy weight gain with your doctor, midwife or dietitian.

When Should You Seek Medical Advice?

Regular antenatal appointments are especially important if you have diabetes during pregnancy.

Contact your healthcare team if:

• your blood glucose levels are repeatedly above your recommended range
• you experience frequent episodes of low blood glucose while using diabetes medication
• you become unwell or are unable to eat or drink normally
• you are concerned about your baby’s movements
• you have any new or worrying symptoms during pregnancy

Symptoms such as severe dizziness, confusion, fainting or significant illness should be assessed promptly.

For additional information about diabetes symptoms and management, see Healthdirect.

Support During Pregnancy

Your doctor, midwife, diabetes educator, dietitian and pharmacist can all play a role in helping you manage the condition.

You may also be eligible to register with the National Diabetes Services Scheme (NDSS), which provides diabetes information, support and access to subsidised diabetes products.

Your healthcare professional can explain which services are available to you.

Speak With Your Pharmacist

Your MediAdvice pharmacist can help with practical aspects of managing diabetes during pregnancy, including:

• using blood glucose meters
• understanding testing supplies
• insulin injection technique where prescribed
• medicine-related questions
• general diabetes management advice

Your pharmacist can also refer you to your doctor or another healthcare professional when further assessment is required.

General advice only: This information is not intended to replace advice from your doctor, midwife, diabetes educator or other healthcare professional. If you have concerns during pregnancy or your symptoms are severe or persistent, seek professional medical advice.