Gestational Diabetes Mellitus (GDM) is a condition that develops during pregnancy when an expectant mother’s body does not cope well with the demand for increased insulin production; leading to elevated blood glucose levels.¹ In Australia, best practice is to offer every woman a glucose tolerance test at between 26-28 weeks gestation² – this involves a drinking a sugary drink and having blood taken. This test is designed to check your body’s response to the controlled amount of glucose (a type of sugar) within the drink. The blood test checks the glucose level and compares it to the diagnostic criteria. If any of the glucose levels are higher than the reference range for that time period, your doctor may diagnose you with GDM. After a diagnosis, the doctor may refer you onto a Dietitian, Endocrinologist and/or Credentialed Diabetes Educator to help manage your blood glucose levels. As a Dietitian, I hear many questions and theories behind the development of the condition and its management. These are my Top 5 Gestational Diabetes Myths.

1. MYTH: Eating a slice of cake (or two) will cause you to develop gestational diabetes.

Monitoring dietary carbohydrate is an important component of diabetes management. Nutrition is an important part of a healthy pregnancy, however carbohydrates (including sugars) do not cause a women to develop gestational diabetes. Often during pregnancy, many women use the excuse of “I’m eating for two” to overindulge; and although this has some merit, the extra energy required during pregnancy doesn’t start to increase until the second trimester and peaks in the third trimester. These increases are equal to the energy in a tuna and salad sandwich or nut bar and yoghurt and should come from nutrient dense (healthy) food options. Excess energy in the diet leading to excessive weight gain during pregnancy increases the risk of GDM,¹ but this it not directly linked to a certain food within the diet.

2. MYTH: All women with gestational diabetes will have big babies.

A complication of uncontrolled diabetes during pregnancy is an increase in the birth weight of the baby.^1,4 This is due to the mechanism of increased insulin and glucose levels in the mother, which, during pregnancy, is then passed through the placenta onto the foetus and extra energy is used for growth⁴, leading to a bigger baby. Having said this, women who have controlled GDM, reduce the risk of having a baby with a larger birth weight.

3. MYTH: All women with gestational diabetes will not have diabetes once the baby is born.

90% of women who are diagnosed with diabetes during pregnancy will not have diabetes after delivery. The remaining 10% potentially had diabetes prior to pregnancy, but it went undetected. In Australia it is estimated that there are 1.7 million people who have diabetes¹, with an additional 25% estimated to be undiagnosed.⁵ There is also a 10 fold increased risk of developing type 2 diabetes after being diagnosed with gestational diabetes in the following 10 years.³ So although chances are you will no longer have diabetes after delivery, a healthy lifestyle can help reduce the risk of developing diabetes later on.

4. MYTH: Only overweight women develop gestational diabetes

Being overweight prior to pregnancy has been associated with an increased risk of developing GDM.¹ Weight gain during pregnancy is also an important factor in the development of GDM. There are also other non-modifiable risk factors for GDM including ethnicity, age and family history. ¹ Some women have no risk factors and still develop the condition, which is why there is a best practice guideline to test all women for GDM during pregnancy. So although being overweight does increase the risk of developing GDM, there are many factors that contribute to the condition.

5. MYTH: I will need insulin to manage my gestational diabetes

Insulin is a hormone produced by the body to help control blood glucose levels. Insulin replacement therapy is a medical strategy helpful for controlling blood glucose levels in women with gestational diabetes when other lifestyle and medication are not effective. Not all women require insulin to control their blood glucose levels; often first line of management is lifestyle changes including both diet and physical activity. Only 10-20% of women with GDM will require insulin.¹ Take home

• Carbohydrates alone are not responsible for developing GDM
• Dietary management often involves monitoring total carbohydrate intake and spread throughout the day to control blood glucose levels
• The quality (e.g. how quickly the carbohydrate is released into the bloodstream) of the carbohydrate option at the meal will help with blood glucose control
• Dietitians play an important role in the management of GDM and reducing the risk of developing diabetes later in life

Dietetic services are available with one of our Accredited Practicing Dietitians; Samantha Delahay and Melissa Edwards at our Penrith, Westmead and Norwest rooms. References:

1. Diabetes Australia; 2015; Managing gestational diabetes (online). Available from: https://www.diabetesaustralia.com.au/managing-gestational-diabetes. Last Accessed: 27.9.18
2. RANZCOG; 2017; Diagnosis of Gestational Diabetes Mellitus (GDM) (online). Available from: https://www.ranzcog.edu.au Last Accessed: 29.9.18
3. Herath et al 2017; Gestational diabetes mellitus and risk of type 2 diabetes 10 years after the index pregnancy in Sri Lankan women—A community based retrospective cohort study. PLoS One; v.12(6) 2017
4. K, Kc et al; 2015; Gestational diabetes mellitus and macrosomia: a literature review. Ann Nutr Metab. 2015; 66 Suppl 2:14-20
5. Australian Government; 2017; Diabetes in Australia: Focus on the future. Australian Government of Australia 2017