An overview of Gestational diabetes

Gestational diabetes mellitus, or GDM, is becoming an increasingly more common problem amongst pregnant women, now affecting between 5-8% of all pregnancies. This is equal to about 1 in every 15-20 women.

What is Gestational Diabetes?

Gestational diabetes describes the time when your body is said to be in a state of “hyperglycemia”, or simply too much glucose present in your blood. The condition is limited to your pregnancy only which means that it is first diagnosed whilst pregnant and disappears not long after delivery of your baby, with your glucose levels returning to normal.

What causes it to develop during my pregnancy?

Gestational diabetes is a multifactorial condition, meaning there are a variety of factors that contribute to why it develops in certain pregnancies and not others.  One physiological explanation is that during pregnancy the placenta produces hormones to help the baby grow, however sometimes these can interfere and block the action of your normal bodily hormones such as insulin. Insulin is responsible for transporting glucose from the blood into cells where it is used for energy; if there isn’t enough insulin then there will be too much glucose left in the blood and your blood glucose levels will rise and cause diabetes. Your body does attempt to try to produce more insulin however sometimes this isn’t enough.

Other factors that increase your risk of developing Gestational diabetes include:

  • Age – If you are older than 24 years of age at the time of pregnancy, you have 7-10 times greater chance of developing Gestational diabetes.
  • History of Gestational diabetes in your previous pregnancies
  • Being overweight or obese
  • History of large babies over 4kg in weight at birth
  • Polycystic ovarian syndrome
  • Family history of Gestational diabetes or Type 2 Diabetes Mellitus
  • Ethnicity – Being of Indigenous, South Asian, Vietnamese descent

How will GDM affect my pregnancy?

This condition can affect your pregnancy in a variety of ways, ranging from mild symptoms to more servious… which all depend on how well the disease is controlled.

  • Premature delivery – You may go into labour prematurely, or at a date earlier than your expected one.
  • Large for gestational age baby – Your baby is exposed to very high sugar levels as glucose travels freely from your blood, across the placenta to the fetus. The baby will produce excessive amounts of insulin in efforts to reduce its own blood sugar level.  Insulin is also a growth hormone; thus as more insulin is produced, this can lead to accelerated growth of your baby and subsequent large birthweight. Large babies are described as a weight of 4.0g kg at term, and if equal to or greater than 4.5kg then your baby is described as having ‘macrosomia.’
  • Injury to the baby during labour – Large babies are at risk of shoulder dystocia whereby the infant’s shoulder gets stuck during delivery which is an obstetric emergency, or can suffer from bone fractures or nerve palsies body structures being compressed as baby is pushed out.
  • Obstructed labour – This occurs when your labour progression slows to a halt due to the baby not moving down through pelvis adequately. This is most commonly due to a large birthweight size in this scenario. If this occurs it is more likely that assisted delivery is needed with either forceps or vacuum to aid with the delivery of your baby, or an emergency caesarean section.
  • Higher risk of developing pre-eclampsia, the blood pressure disease of pregnancy.
  • Newborn issues – Your baby is at a greater risk of developing hypoglycaemia or low blood sugar levels after delivery, as well as respiratory distress syndrome, and may be required to be admitted to intensive care unit and stay in hospital for longer period of time.
  • Risk of childhood disease –Your child will be at increased risk of developing obesity, Type 2 Diabetes mellitus, and metabolic syndrome.
  • Risk of maternal disease – You will have an increased risk of developing Type 2 Diabetes Mellitus (30-70%), gestational diabetes in future pregnancies, obesity and metabolic syndrome.

How do I know if I have Gestational Diabetes?

  • Every pregnant woman gets screened for Gestational Diebtes as part of her routine antenatal care.
  • You will have a Glucose Challenge Test (GCT) between 26-28weeks of your pregnancy. This is a non-fasting test whereby you will drink 50g glucose drink and have two blood tests after, taking approximately 1 hour.
  • If this result is positive then you have another test called Glucose Tolerance Test (GTT). This is a fasted test, involving a 75g glucose drink and 3 blood tests over 2 hours.  If this test result is positive, you are diagnosed with Gestational Diabetes.

How can I help prevent this condition developing?

There is no specific diet for preventing the development of Gestational diabetes. However both high fibre diets and low glycaemic-index diets have shown to improve your body’s insulin sensitivity and glucose tolerance. This means avoiding high sugar foods and opting for more complex carbohydrate choices, which have a much smaller effect on your blood glucose levels, and substituting sugar with foods that contain minimal amounts of sugar, as shown in the recipe below. This is discussed further in the blog titled ‘Diet Recommendations in Gestational Diabetes.’

Physical activity also reduces the risk of developing diabetes by half through improving the body’s sensitivity to insulin, and helping facilitate weight loss which overall improves glucose control. It is recommended that once falling pregnant you should exercise regularly for at least 30 minutes every day, however avoid excessive or intense activity and stay well hydrated.


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