Gestational diabetes mellitus (GDM) is a form of diabetes that occurs during pregnancy. It affects around 15% of pregnancies in Australia. Due to the significant number of women diagnosed and the possible health impact it can have for both mum and baby, GDM is routinely screened between 24-28 weeks during the pregnancy with an Oral Glucose Tolerance Test (OGTT). This may be completed earlier if there are known risk factors.

During pregnancy, hormones produced by the placenta can reduce the action of insulin.

Insulin is a hormone

Insulin is the hormone needed to move glucose from the bloodstream into the cells in the body to be used for energy after eating food containing carbohydrates. With the action of insulin not working as well, the pancreas has to work harder and may not be able to produce enough insulin. This in turn leads to higher blood glucose levels.

Once diagnosed with GDM, a mother will need to work with her treating team to ensure blood glucose levels stay within a target range. Sometimes this is managed through lifestyle adjustments such as diet and exercise; however, some women may need some additional help through medication or insulin.

Glucose crosses to the baby

The reason higher blood glucose levels need to be avoided is that the extra glucose in the body can cross via the placenta to the baby and make them grow too big. This can lead to problems before, during and immediately after labour.

Once the baby is delivered the blood glucose levels of the mother usually returns to a normal range, which means they no longer have diabetes. For some woman, however, they may continue to have elevated glucose levels, in which case they now have either pre-diabetes or type 2 diabetes.

60% develop type 2 diabetes or pre-diabetes

Importantly, it is now understood that about 60% of woman who had GDM during pregnancy will go on to develop pre-diabetes or type 2 diabetes within 10-20 years. There is also a much higher risk of GDM in future pregnancies.

So after pregnancy, what should a Mum who had GDM know and be aware of?

In the immediate days and weeks after giving birth, life is most likely chaotic as mum and family adjust to their new life with a newborn. Although this can be a stressful period, it is important to ensure the mother remains connected with her health care team and follows some general advice and guidance.

From a food perspective it is important for a new mother to nourish her body with foods rich in vitamins, minerals and good quality sources of energy.

There is strong evidence of the benefits breastfeeding can have on reducing future type 2 diabetes for both mother and baby. If diagnosed with either pre-diabetes or type 2 diabetes after birth, breastfeeding is also highly effective for helping the mother manage her blood glucose levels.

Here are some general steps for a GDM Mum to follow once her baby is delivered.

1. Ensure regular diabetes checks after birth – Between 6-12 weeks after delivery, an OGTT is recommended. It is believed 1 in every 5 women post pregnancy will still have higher blood glucose levels. Even if type 2 diabetes is not picked up during the screening it is recommended to repeat this test every 1-3 years depending on the level of risk.
2. Making healthy food choices – There is no specific diet when preventing or living well with type 2 diabetes. Choose a diet rich in vegetables, wholegrains, and legumes with moderate amounts of fruit, dairy, lean protein sources and healthy fats. Aim to reduce highly processed options and foods high in fat, sugar, energy and salt, which will help reduce insulin resistance and type 2 diabetes risk.
3. Being active every day – Physical activity helps reduce insulin resistance by making the muscles thirsty for glucose. As a general guide, aiming for 30 minutes of exercise per day will assist in ongoing management of blood glucose levels. Seeking out the support of an Exercise Physiologist can be helpful in the post-partum period.
4. Aiming for a healthy weight – As a new mum it can be tricky to engage in health-gaining behaviours such as moving more, enjoying healthy food choices and getting sleep when you can etc, which can all result in weight changes. It is important to encourage women to aim as best they can to engage in health-gaining behaviours when and where they can, regardless of weight shifts, as these behaviours can reduce the future risk of type 2 diabetes or future GDM pregnancies.

Planning another pregnancy?

• Continue to follow the steps provided above.
• All women need to get tested earlier in the pregnancy, usually before 16 weeks and or when the nausea dies down.
• If you have already been diagnosed with pre-diabetes or type 2 diabetes it is also highly recommended to consider the following:

1. See the Doctor/GP 3-6 months before planning another pregnancy (see booklet page 27 for checklist to assist planning a pregnancy with type 2 diabetes).
2. Once pregnant, be referred to a specialist for close monitoring during the pregnancy.

For more information please refer to the NDSS Life after gestational diabetes booklet or call the National Diabetes Services Scheme (NDSS) Helpline on 1800 637 700.

By Linda Uhr, Diabetes NSW & ACT Accredited Practising Dietitian & Diabetes Educator