Making sense of gestational diabetes – diagnosis and diet

What is gestational diabetes? 

Gestational Diabetes Mellitus (GDM) or gestational diabetes (GD) is a type of diabetes that occurs during pregnancy. It is diagnosed following a 2-hour Oral Glucose Tolerance Test (OGTT) at around 24 to 28 weeks of pregnancy.  

Some women whose health, pregnancy or family history put them at a higher risk will also have this test early in their pregnancy.  

The OGTT is a blood test ordered by your GP, obstetrician, or antenatal clinic. This is considered a ‘universal test’, which means all pregnant women should have this test. 

Why do some women get GDM? 

GDM occurs as a result of changes in hormone levels as pregnancy progresses. These changes  can interfere with how some women’s insulin works. Insulin usually helps process glucose from the blood into the muscles (for energy) and liver (for storage and energy).  

What happens if my blood glucose levels stay too high in late pregnancy? 

If high blood glucose levels (BGLs) are not treated, a number of problems can be seen in a pregnant woman or her baby.   

Women with poorly-controlled BGLs are at much higher risk of developing type 2 diabetes mellitus after pregnancy. This risk increases when women are not supported to follow a healthy lifestyle or to healthily lose their pregnancy weight.  

A woman with GDM can have a baby that has an unhealthy growth pattern before it is born.  A baby’s insulin still works well so, even in utero (in the womb), it is able to store extra glucose and will grow faster and fatter. This means the growing baby can be at risk of: 

  • being a very large baby,  
  • having early delivery, 
  • being distressed during birth, and/or
  • having low blood glucose levels at birth.  

Babies born to mums whose BGLs have been higher than ideal, without good support for BGL management, are also more likely to be overweight or obese into their adult lives and have diabetes themselves.   

So, do I have to cut all sugar out of my diet to control my blood glucose levels? 

No. Although some foods we eat (carbohydrates) put glucose into our blood stream, cutting these foods out completely means we cut out all the nutritious goodness we need for a healthy pregnancy and a growing and developing baby. We also need carbohydrates to run our body – without them it is like a car running out of fuel. 

GDM is primarily managed by following a healthy well-balanced eating plan, taking into consideration carbohydrate intake and physical activity. If women’s BGLs are unable to be managed with diet and activity alone, medication such as insulin (injections) or metformin (tablets) are sometimes needed.   

Ongoing, regular contact with Diabetes Educators, Dietitians, and medical specialists during pregnancy is important for good BGLs and best outcomes for mother and baby.  

How many visits should I have with a dietitian? 

All studies point to the benefits of ongoing contact and support from an expert maternal health dietitian when managing your GDM. Studies testing the effectiveness of GDM nutrition guidelines have shown improved pregnancy outcomes (less need for insulin and better control of blood glucose levels) when women saw a specialist maternal health/GDM dietitian a minimum of three times during their pregnancy and a postnatal review 

Our Director and Principal Dietitian, Dr Shelley Wilkinson, has applied these findings in health services she has worked in and collaborated with and now brings them to Lifestyle Maternity. Our specialist maternal health-GDM dietitians are able to tailor a program to support you to adapt guideline recommendations to your lifestyle and preferences. If you need support, please make an appointment to help you achieve your goals. 


IMAGE CREDIT: Unsplash, Paul Lin 

IMAGE DESCRIPTION: Pregnant woman standing outside, side on, looking down at an orange gerbera