A diagnosis of Gestational diabetes for many pregnant women can bring on a sense of disempowerment and confusion, wondering what could have been done and why more measures weren't taken to avoid it. Whilst many mums are relieved to find out the dreaded Glucose Tolerance Test is negative, we now know that Gestational Diabetes Mellitus (GDM) is the fastest growing type of diabetes in Australia. Around 12% to 14% of pregnant women develop gestational diabetes – that’s around 68 women everyday! Around 10 – 20% of women with GDM will need insulin, however this is usually not required after baby is born.
There are several risk factors, and women who have known risk factors are usually screened earlier in pregnancy. Women at increased risk of developing gestational diabetes include:
Aged 40 years or over, or have a family history of type 2 diabetes or gestational diabetes
Are above the healthy weight range, based on BMI.
Have had elevated blood glucose levels in the past or had gestational diabetes during previous pregnancies
Are from Aboriginal and Torres Strait Islander backgrounds
Are from a Melanesian, Polynesian, Chinese, Southeast Asian, Middle Eastern or Indian background
Have previously had Polycystic Ovary Syndrome
Have previously given birth to a large baby (weighing more than 4.5kg)
Are taking some types of anti-psychotic or steroid medications
Have gained weight too rapidly in the first half of pregnancy.
Source: Queensland health
However, women with no known risk factor may also go on to develop Gestational diabetes, highlighting the effect of pregnancy and placental hormones on usual glucose metabolism.
So what is Gestational Diabetes?
Gestational diabetes is an intolerance to glucose that begins in pregnancy. GDM is usually tested between 24-28 weeks, or earlier for those who have risk factors present. This is tested at 1 and 2 hours after ingesting a set load of a simple sugar solution. A diagnosis of gestational diabetes is made based on either fasting or post-prandial glucose response. The diagnosis differentiates from Diabetes in Pregnancy based on blood glucose parameters during testing.
Source: Queensland health
Diagnostic criterion have changed over the last few decades, and Australia’s cut offs differs from other international criteria. However, we know that eating well and moving well in pregnancy, as well as before and after pregnancy, is so beneficial for both mum and bub.
Why does it occur?:
A normal pregnancy causes changes to fat and carbohydrate metabolism to assist with various stages of fetal development. Oestrogen and progesterone change usual glucose and insulin functioning, and human placental lactogen, growth hormone and cortisol also causes changes in glucose and fat metabolism.
Early pregnancy is an anabolic state in the mother and there is an increase in insulin sensitivity – meaning the body prepares by storing nutrients for the upcoming needs for baby.
Late pregnancy (around >24 weeks) is a catabolic state where there is a decrease in insulin sensitivity (more resistance) - this allows nutrients to be directed to the growing baby.
Gestational Diabetes occurs when mum’s pancreas is unable to release enough insulin, or the sensitivity of insulin decreased. This keep more floating around in her blood, and goes to baby.
Why is it important to manage it optimally?
Gestational diabetes may be managed through lifestyle and also medication to avoid complications for both mum and baby. If it is not appropriately managed, high blood sugars in the mother lead to a transfer of glucose through the placenta, which stimulates the beta cells of baby’s pancreas to release more insulin. Ongoing elevated insulin levels increase the risk of fetal macrosomia (excessive growth in utero), neonatal hypoglycaemia (low blood glucose levels), respiratory distress syndrome, jaundice and premature birth, among other complications. (Queensland health)
Many treatment options exist to support the best outcomes for both mum and baby, including individualised dietary strategies with an Accredited Dietitian and a pregnancy stage appropriate physical activity plan with an Accredited Exercise Physiologist.
Carbohydrates are essential in pregnancy, providing energy, vitamins, minerals and fibre for mother and baby. Individualised targets for total energy from carbohydrates are a large part of management goals, however a minimum 175 g of carbohydrate per day , or ~11-12 carbohydrate exchanges/ day (1 exchange is ~15 grams of carbohydrates), is recommended to meet the needs of fetal brain development.
The focus within the diet is:
Quality – wholegrain, high fibre varieties of bread, cereals etc.
Quantity – aiming for controlled portions of carbohydrates, usually tracked in the form of exchanges.
Timing – spreading the intake of good quality, well portioned amounts of carbohydrates throughout the day allows for more steady blood glucose levels.
Understanding carbohydrate quantities in common foods can help with monitoring and spreading your intake:
Figure: Queensland Health
Movement and exercise can be a key strategy in managing optimal blood sugar levels. This is because exercise increases the movement of glucose from the bloodstream to body cells, independent of insulin. That is, no matter how insulin resistant, muscles help soak up high blood sugars because exercise training alters expression of muscle proteins to make the body more responsive to insulin. Additionally, higher physical activity levels prior to pregnancy and during early pregnancy are associated with a significantly lower risk of developing gestational diabetes.
For optimal management, the physical activity guidelines suggest a mixture of both aerobic exercise and strength training. Things you can do include walking, swimming, yoga, pilates, light resistance training, body weight exercises. Ideally, build up to 30 minutes 5 days per week, and 8 – 12 different strength exercises on around 3 days/ week. These strength exercises should target major muscles all over the body as activation of large muscles improve glucose uptake. Additionally, focusing on pelvic floor exercises early in pregnancy can be useful to create a habit in the post-natal period. For more, see the previous post on the Pelvic Floor.
When it comes to exercising with Gestational Diabetes, the key is managing your blood glucose levels before, during, and after exercise. Getting individualised support during Gestational diabetes is essential, but here are some considerations:
Aim for moderate intensity, using a rate of perceived exertion of around 6-7 out of 10. You can also use a talk test, where you would be able to maintain a conversation but not be able to sing (if you are into that). The good thing about this method is that you can adapt the intensity to the different stages and needs of your pregnancy.
Exercise in cooler periods of the day - stay hydrated and wear comfortable clothing (e.g. supportive bra and shoes)
Additional carbohydrates may or may not be needed to meet energy needs and to avoid low blood glucose levels. This is an important consideration if you have been prescribed insulin, but be sure to speak to your doctor or diabetes educator about your needs.
Monitor and record your blood glucose levels prior to and one hour after exercise, and be aware of symptoms of hypoglycaemia (low blood glucose levels) as this can happen up to 48 hours after moderate levels of exercise. Review your levels with your healthcare team.
Be aware of signs or symptoms where exercise may be best to avoid or stop. For more tips on safety when starting exercise with Gestational Diabetes, see the Exercise is Medicine factsheet on Pregnancy and Exercise, and speak to your doctor, diabetes educator or exercise physiologist to help.
No matter what stage of pregnancy you are in, becoming and staying active has many benefits aside from stabilising blood sugars. From posture, to pain, to improved birth outcomes and quicker recovery, the list goes on. The most important thing is finding activities that you enjoy, and are able to participate in regularly so that you continue to stay active.
By knowing how to eat well and how to move well, you can take back the confidence in managing healthy blood glucose levels and an healthy pregnancy overall.
The information contained in this post for general information only and does not replace the guidance from your healthcare team.