Gestational Diabetes and Pregnancy – what you need to know

Gestational Diabetes and Pregnancy – what you need to know


·  Gestational diabetes mellitus or GDM, is one of the most common diet related complications in pregnancy.

·       Gestational diabetes is caused by an improper insulin response in your body; this means that sugar levels are abnormally high, although no diabetes was diagnosed before pregnancy.  So, GDM isn’t the same as suffering from other forms of diabetes before getting pregnant.

·       In gestation, the placenta produces hormones that help the baby to grow and develop. These hormones also block the action of the insulin, which is the hormone that helps to keep glucose (or blood sugar) at normal levels. This is called insulin resistance. Because of this insulin resistance, the need for insulin in pregnancy is 2 or 3 times higher than normal. If the body is unable to produce this much insulin, gestational diabetes develops.

·       GDM is most commonly diagnosed around the third trimester (usually around the 24th to 28th week of pregnancy) and in most of the cases goes away once the baby is born.

·       While maternal blood glucose levels usually return to normal after birth, there is an increased risk for the mother developing type 2 diabetes in the future.


·       The prevalence of diabetes during pregnancy has been increasing markedly around the world, and it is closely associated with the rise of obesity and sedentary lifestyle. However, even women with a healthy BMI can be affected, due to pregnancy-related factors.

·       12-14% of all pregnant women develop gestational diabetes; although, the incidence is higher in certain ethnic groups. In Australia, more than 35,000 women develop gestational diabetes every year; the incidence rate in our country is highest among women aged 30–34 years.


The following are cases where women are at greater risk of developing gestational diabetes:

  • Mothers who are over 30 years of age
  • Having a family history of type 2 diabetes
  • Women who are overweight or obese
  • Are from Indigenous Australians
  • Women from certain ethnic backgrounds including: Vietnamese, Chinese, middle eastern, Polynesian or Melanesian.
  • Women who have had gestational diabetes
  • Women who have had large babies or obstetric complications
  • Woman who have had polycystic ovarian syndrome


·       GDM is a treatable condition, and women who have adequate control of glucose levels can successfully decrease the adverse outcomes associated with this complication of gestation.

·       Gestational diabetes is associated with an increased risk of complications in pregnancy and birth, as well as a greater likelihood of mother and child developing type 2 diabetes later in life. The good news is that with good management of gestational diabetes, these risks are significantly reduced.

·       The mother has a higher risk of: abortion, hypertension, preeclampsia, caesarian delivery, and labor complications.

·       The infant is at increased risk of: macrosomia (defined as a weight of more than 4 kg at birth), large-for-gestational age, shoulder dystocia, neonatal hypoglycemia and perinatal morbidity and mortality; moreover.

·       Compared to the children of mothers without GDM, the babies of women diagnosed with this condition have increased rates of cognitive and motor abnormalities, including attention deficit hyperactivity disorder, learning difficulties, and autism.

·       The risk of adverse maternal, fetal and neonatal outcomes increases proportionally to the degree of maternal hyperglycemia. These means that a woman diagnosed with GDM who can keep her blood sugar at target levels will present fewer complications, for her and her baby.


·       Typically, gestational diabetes does not present with easily recognizable symptoms. This is why all pregnant women should be tested for gestational diabetes by taking a special blood test.

·       Screening and diagnosis of diabetes during pregnancy is important for one main reason: to have a proper management and treatment of hyperglycemia during pregnancy and to improve maternal and neonatal outcomes.

·       Although there are two common screening practices used to detect GDM, the World Health Organization advocates for a universal one-step diagnostic approach after 24 weeks of gestation. The one-step approach which is the oral glucose tolerance test, or OGTT is used to check how your body responds to a glucose load. After fasting for 8-12 hours, a blood sample is taken. You then have a drink containing 75g of glucose and blood samples are taken again one and two hours later. GDM diagnosis is made when one glucose value falls at or above the specified glucose threshold.

There is the two-step approach or OGCT, Oral Glucose Challenge Test. This is a non-fasting test where 50 gr of glucose is administered. And plasma glucose levels are evaluated after one hour. If the screening threshold of 7.8 mmol/l is met or exceeded, a second step or OGTT is performed.

·       Blood glucose self-monitoring should be performed to allow treatment follow-up. Glucose targets for a woman suffering from GDM should be fasting under 5.3 millimoles per liter. And either one hour postprandial under 7.8 millimoles per liter, or two hours postprandial under 6.7 millimoles per liter.



·       Once gestational diabetes has been diagnosed, treatment starts adopting a healthy eating plan, performing regular physical activity and weight management for those women who have had a weight gain above of what is expected.

·      Evidence has proven that around 70 to 85% of women with GDM are able to control hyperglycemia with lifestyle modification alone.

·       However, for some women with gestational diabetes, insulin injections will be necessary for the rest of the pregnancy. Approximately 10 – 20% of women will need insulin, though, once the baby is born insulin is no longer needed.



·       The optimal dietary prescription would be a diet that provides adequate nutrition to support fetal and maternal well-being, while maintaining normoglycemia and achieving appropriate weight gain in pregnancy.

·       All diets should be individualized for pregnant women with GDM, however, it is recommended to follow a low saturated-fat, low-sugar diet; it is also advisable:

o   Eat small portions of food often and maintain a healthy weight

o   Avoid foods and drinks containing substantial amounts of sugar, like soft drinks, fruit juices, cakes and biscuits. The use of artificial sweeteners is preferable.

o   Include some carbohydrate in every meal and snacks, ideally high in fiber. Foods that contain carbohydrate include:

  • Multigrain breads and breakfast cereals
  • Pasta, rice and noodles
  • Legumes such as baked beans, red kidney beans and lentils
  • Fruits
  • Milks and yogurts

o   Try to limit the amount of fat you eat, particularly saturated fat; preferable to use fats like canola, olive and polyunsaturated oils and margarines, avocados and unsalted nuts

·       If your blood sugar levels remain high despite changes to your diet and an exercise regime, then medication, usually in the form of insulin, will be recommended to lower the blood sugar levels into the normal range.



·       After the baby is born, gestational diabetes usually disappears. A Oral Glucose Tolerance Test is performed six weeks after delivery to ensure that blood glucose levels have returned to normal. However, women who have had gestational diabetes have an increased risk of developing type 2 diabetes later in life and should be tested for diabetes at least every 2 – 3 years.

·       That is, a dietary plan and appropriate levels of physical activity. When lifestyle management is insufficient for glycemic control, pharmacological treatment may be necessary.

Therefore, postpartum follow-up for affected women is recommended. The oral glucose tolerance test is recommended at the six and twelve-week postpartum visit.

·       Up to 50% of women with GDM later will develop Type 2 Diabetes.

Recent studies have demonstrated that women with a history of GDM who adopted healthy eating patterns and increased physical activity after birth, had a significantly reduced risk of developing Type 2 diabetes. Therefore, it is really important to offer lifestyle advice to women with a history of GDM.



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*     Zhu, Y., & Zhang, C. (2016). Prevalence of Gestational Diabetes and Risk of Progression to Type 2 Diabetes: a Global Perspective. Current Diabetes Reports, 16 (1). http://dx.doi.org/10.1007/s11892-015-0699-x

*     Silva-Zolezzi, I., Samuel, T., & Spieldenner, J. (2017). Maternal nutrition: opportunities in the prevention of gestational diabetes. Nutrition Reviews, 75(suppl 1), 32-50. http://dx.doi.org/10.1093/nutrit/nuw033

*     (2018). Diabetesqld.org.au. Retrieved 19 March 2018, from https://www.diabetesqld.org.au/media/33447/gestational_diabetes_booklet.pdf

*     Managing gestational. (2018). Diabetesaustralia.com.au. Retrieved 19 March 2018, from https://www.diabetesaustralia.com.au/managing-gestational-diabetes

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