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Diabetes in pregnancy

Diabetes is a condition in which your blood sugar (glucose) level is high because there isn't enough of the hormone insulin in your blood, or your body isn't responding to insulin properly. Normally, the body releases insulin after eating to help glucose enter the body cells where it provides nourishment. Insulin helps to keep blood glucose levels to within narrow limits in this way. Diabetes occurs when insulin is either not being produced or the insulin that is being produced is not controlling the levels of glucose in the blood effectively.

During pregnancy, the placenta produces hormones that help your baby grow and develop but they can also affect the action of the insulin. In response, your body has to produce more insulin — you need two or three times more insulin than normal while you are pregnant. If your body isn’t able to produce this much insulin, or if your body becomes resistant to the action of insulin, your blood glucose levels rise to higher than normal levels, leading to gestational diabetes.

Gestational diabetes usually goes away after your baby is born. It may return with subsequent pregnancies though, and having gestational diabetes puts you at greater risk of developing type 2 diabetes, a chronic (long-term) condition.

Could you be at risk of gestational diabetes?

Gestational diabetes is thought to affect about five percent of women in Australia and you may be at a higher risk of developing gestational diabetes if you:

  • are aged over 30
  • have a family history of type 2 diabetes
  • have had gestational diabetes in a past pregnancy
  • are overweight or obese
  • had a very large baby (4.5kg or over) in a previous pregnancy
  • have polycystic ovary syndrome (PCOS)
  • are an Indigenous Australian or of Torres Strait Islander origin
  • are of Indian, Chinese, Vietnamese, Middle Eastern, Polynesian and Melanesian origin.

Symptoms of gestational diabetes

Gestational diabetes may not have any obvious symptoms. Sometimes you may have symptoms of high blood sugar which can include:

  • excessive thirst
  • increased need to urinate often
  • fatigue.

However, these are also common symptoms of a normal pregnancy.

Complications of gestational diabetes

While gestational diabetes may not be an immediate threat to your health, if the condition isn’t managed well, it can increase your risk of other health issues, including:

  • pre-eclampsia (high blood pressure during pregnancy)
  • premature labour
  • having too much amniotic fluid (the fluid around your unborn baby)
  • type 2 diabetes.

The higher-than-normal levels of blood glucose circulating in your blood can also affect your unborn baby. Your baby:

  • may be larger than expected — your baby will need to make extra insulin to control the increased blood sugar, which causes more fat and tissue to be stored. A bigger baby can make delivery more difficult.
  • may have low blood sugar after birth — shortly after birth, your baby may still be making extra insulin, causing their blood sugar level to be too low.
  • may be at risk of jaundice — this is a condition where there is yellowing of the skin and whites of the eyes. This usually fades without the need for medical treatment.
  • may be at increased risk of becoming obese as a child — this can also lead to an increased risk of developing diabetes during childhood.

There is also a slightly higher chance of stillbirth or death as a newborn, but this is rare as long as blood sugar levels in both you and your baby are well controlled.

Diagnosis of gestational diabetes

Gestational diabetes is usually detected in the 24th to 28th week of pregnancy when you have a routine glucose test, although it can develop and be detected earlier.

For the glucose test, you will be given a glucose-containing drink. After an hour, you will be asked to have a pin prick test that measures the glucose in a tiny amount of your blood. A higher than normal result will be followed by a specific test called an oral glucose tolerance test (OGTT). After an overnight fast, you will be given a drink that contains glucose and your blood will be measured for glucose before the test, one hour after it and then again an hour later. High levels of blood glucose confirm gestational diabetes.

Treating gestational diabetes

If you are diagnosed with gestational diabetes, your healthcare team will advise you on how to effectively control your blood glucose levels in several ways.

  • Diet. Eating a varied diet that contains carbohydrates from whole grains, cereals, fruits, pasta and rice in small meals throughout the day is usually advised. These low glycaemic index (GI) carbohydrates take time to be digested because they contain fibre and provide a slow and steady release of glucose – not the rapid rises you’ll see after eating paler versions which have had their fibre removed or after eating sugary carbohydrates. Overall, your diet should be healthy and well-balanced with these slow absorbing carbohydrates and a variety of lean proteins such as oily fishy, as well as at least five portions of fruit and vegetables each day. You may be asked to see an accredited practising dietitian, especially if you have special dietary concerns. Your diabetes educator can also give you advice.
  • Exercise. Regular physical activity such as walking/swimming helps to control blood glucose levels and improve fitness. Regular exercise helps your body control your blood glucose levels by encouraging the movement of glucose into your cells. It also increases body cells’ sensitivity to insulin. The National Physical Activity guidelines recommend that adults get at least 30 minutes of moderate-intensity physical activity (that is, exercise that gets you slightly breathless) on most, preferably all, days of the week. Before you start a new exercise program while pregnant, check with your doctor first to make sure the activity is appropriate for you.
  • Monitoring blood glucose levels. This is essential to determine whether the treatment is helping to moderate your blood glucose levels so that it can be adjusted if necessary. Your doctor or your diabetes educator will be able to show you how to test your blood glucose level, how often to do it, and what levels you should be aiming for.
  • Medicines. If diet and exercise is not controlling your blood glucose levels well, you may need to use insulin injections to keep the blood glucose levels to within a normal range. Your doctor and your diabetes educator will provide you with all the information and support you need. This treatment is safe during pregnancy and insulin won’t cross the placenta and affect your baby.

Gestational diabetes and childbirth

If your diabetes is well controlled and you don't have any other major health problems, a normal birth is possible. But, you may be offered a planned birth either with induced labour or a caesarean section when your pregnancy has reached 38 weeks if your baby hasn’t arrived before this time.

This is because having diabetes means that your baby may be larger than usual and you may have a more difficult labour. Your midwife and doctor will monitor your pregnancy closely and will discuss your options with you.

After your baby is born

You and your baby will have your blood sugar levels monitored after the birth to make sure they are back to normal.

You will also be asked to have your blood glucose level tested six to eight weeks after the birth of your baby to make sure that it has gone back to its pre-pregnancy levels. Usually diabetes that develops during your pregnancy goes away within a few weeks of the birth of your baby.

However, if you have had gestational diabetes, you are at greater risk of developing type 2 diabetes in the future. You can reduce the likelihood of this by making healthy lifestyle choices that help reduce this risk. This includes eating a healthy and well-balanced diet, regular physical activity and maintaining the right weight for your height.

For more information about healthy lifestyle choices, please see our Healthy Living hub.

Key points about gestational diabetes

  • Gestational diabetes is a type of diabetes that develops during pregnancy. It usually goes away after your baby is born.
  • Women with gestational diabetes have an increased risk of developing type 2 diabetes later.
  • Eating well, exercising regularly and staying in the right weight range for you can help boost your long term health and reduce your risk of developing life-long diabetes.

Further information

Diabetes Australia

Dietitian’s Association of Australia


Australian Diabetes Council. Gestational diabetes. [online] Glebe, NSW: Australian Diabetes Council. c2010 [accessed 27 Jun 2011] Available from:

Diabetes Australia. Gestational diabetes. [online] Canberra, ACT: Diabetes Australia. c2011 [accessed 27 Jun 2011] Available from:

National Diabetes Information Clearinghouse (NDIC). What I need to know about gestational diabetes. [online] Bethesda, MD: NDIC. Apr 2006. [accessed 27 Jun 2011] Available from:

The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG). Diagnosis of gestational diabetes mellitus. Jun 2008 [last reviewed Jun 2011, accessed 27June 2011] Available from:

Mayo Clinic. Gestational diabetes: treatment and drugs. [online] Mayo Foundation for Medical Research and Education. Mar 2011 [accessed 27 Jun 2011] Available from:

Better Health Channel. Diabetes – gestational. [online] Melbourne, VIC: State Government of Victoria. c1999-2010. [last reviewed Feb 2011, accessed 27 Jun 2011] Available from:

Templeton M and Pieris-Caldwell I. Gestational diabetes mellitus in Australia, 2005-06. Cat. no. CVD 44. [online] Canberra: AIHW. 2008 [accessed 27 Jun 2011].

Last published: 30 July 2011

This information has been developed and reviewed for Bupa by health professionals. To the best of their knowledge it is current and based on reputable sources of medical research. It should be used as a guide only and should not be relied upon as a substitute for professional medical or other health professional advice.

Bupa Australia Pty Ltd makes no warranties or representations regarding the completeness or accuracy of the information. Bupa Australia is not liable for any loss or damage you suffer arising out of the use of or reliance on the information. Except that which cannot be excluded by law. We recommend that you consult your doctor or other qualified health professional if you have questions or concerns about your health. For more details on how we produce our health content, visit the About our health information page.

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