The Gestational Diabetes Dilemma

by | Mar 28, 2023 | News

The diagnosis of gestational diabetes, or diabetes onset during pregnancy, has doubled in the past decade, including a 30% increase between 2016 and 2020 alone. Experts predict more than half a million Australian women will be diagnosed with gestational diabetes by 2030. But what are these figures actually telling us, and what changes in birth outcomes are we seeing as a result? Here, I explore all of this and more…

What is gestational diabetes?

I like the simplified description given by Lily Nichols in her book, Real Food for Gestational Diabetes. In it, she describes gestational diabetes mellitus (GMD) as elevated blood sugar during pregnancy, that either develops in pregnancy, or is first diagnosed during pregnancy.

She also explains there are many biologically normal metabolic changes occurring during pregnancy which cause normal fluctuations in blood sugar, resulting from pregnancy weight gain and hormones being secreted from the placenta that interact and interfere with insulin. This causes increased insulin resistance in all pregnancies, which elevates maternal blood glucose levels to ensure adequate amounts can cross the placenta and supply energy to the baby. But for some people, this elevation is more extreme and may require dietary changes and exercise, or in some cases, medications, to manage.

As changes to blood glucose levels are considered a biologically normal occurrence in pregnancy, some experts have questioned the need for routine screening and the validity and value of some testing methods.

In his article “Gestational Diabetes: A Diagnosis Still Looking For a Disease?, esteemed obstetrician and childbirth specialist, Michel Odent described a gestational diabetes diagnosis as “not a disease like with symptoms leading to complementary inquiries, but the mere interpretation of a laboratory test.”

It is essential to emphasize that such a diagnosis is made after the “glucose tolerance test” is included in the battery of tests routinely offered to pregnant women. It is easy to illustrate this fact by referring to the results of a huge Canadian study.(5) In some parts of Ontario routine screening was interrupted in 1989, while it remained usual elsewhere in that state. It became clear that the only effect of routine glucose tolerance test screening was to tell 2.7% of pregnant women that they have gestational diabetes. It did not change the statistics of prenatal mortality and morbidity. 

Odent M, The Journal of Prenatal & Perinatal Psychology and Health (JOPPPAH) Volume 19, Number 2, Winter 2004

What does gestational diabetes mean for me and my baby?

Studies show women who are diagnosed with gestational diabetes are also more likely to develop Type II diabetes in the following years, but this does not indicate causation. Some studies have suggested that women with gestational diabetes may also be more likely to develop preeclampsia and high blood pressure, but these conditions are more likely to be co-morbidities rather than caused by gestational diabetes.

In her book, Gentle Birth, Gentle Mothering, 2009, Dr Sarah Buckley writes it is possible some women with gestational diabetes may actually have mild undiagnosed diabetes, or pre-diabetes, prior to the pregnancy, which becomes ‘unmasked’ by the insulin-resistant effects of pregnancy hormones. Having the diagnosis in pregnancy may also empower women to make dietary and lifestyle changes necessary to reduce their risk of developing Type II diabetes in future.

Dr Buckley states babies born to a mother with gestational diabetes tend to be larger with wider shoulders, which may increase the risk of shoulder dystocia (baby’s shoulder/s becoming stuck in the maternal pelvis during vaginal childbirth) compared to babies of the same weight born to non-diabetic mothers (Buckley, 2009, p 49.) She reveals treating women for gestational diabetes has been found to reduce the chance of having a baby classed as ‘large for gestational age’, or a birth weight over 4kg.

Importantly, Dr Buckley also discusses the possible risks to mother and baby from diagnosing and treating gestational diabetes, (Buckley 2009, pp 50-52.) which includes:

  • Higher rate of caesarean and induction of labour in mothers diagnosed with gestational diabetes
  • Higher risk of babies born to mothers with gestational diabetes having delayed lung maturity, increasing the risks associated with an early birth through induction or caesarean
  • 1 in 50 newborns of mothers with gestational diabetes having hypoglycaemia (low blood sugar) in the hours after birth, which can be treated with breastmilk, or an oral or IV glucose solution. This number may be even higher in mothers who received insulin during pregnancy.

“It has been estimated that over 400 cesareans would need to be done on women with GDM to prevent one baby over 4.5 kilograms from developing permanent nerve (brachial plexus) injury from a traumatic birth.”

Buckley S, Gentle Birth, Gentle Mothering, 2009.

How is gestational diabetes diagnosed?

Most people will receive their diagnosis with gestational diabetes following an oral glucose tolerance test between 24 and 28 weeks gestation. This test usually involves a fasting blood test measuring blood glucose levels, followed by drinking a solution containing 50-75g of glucose (and other additives), and then re-testing blood at one and two hour intervals after drinking the solution. This test is designed to measure how efficiently the body has cleared the glucose from the blood. Gestational diabetes is then diagnosed if the blood glucose levels remain higher than the controversial prescribed parameters, which in Australia is currently:

OGTT results of BGL ≥ 5.1 mmol/l fasting or ≥ 8.5 mmol/l two hours after 75g glucose load.

Interestingly, despite higher insulin resistance and higher blood glucose levels being a normal part of pregnancy, these parameters are far lower than those set for non pregnant diabetes, which is:

OGTT results of fasting BGLs  ≥ 7 mmol/L or BGLs ≥ 11.1 two hours after 75g glucose.

“These thresholds are based on the average BGL (blood glucose level) values that increased the odds of a big baby by 1.75 times. Whilst this threshold may reduce the rates of babies over 4kg, there is no evidence that it will reduce the rate of birth/newborn complications. (Bonventura, Ernest & Dee (2015).”

Reed R, 2018, Gestational Diabetes: beyond the label, Midwife Thinking

What you eat and drink, how long you fast for and any exercise you do before the oral glucose tolerance test may impact your body’s response to the glucose solution. As a result, people who usually eat a low-carbohydrate diet are at higher risk of receiving a ‘false positive’ diagnosis, because their body may be inclined to process the high glucose load of the testing solution at a slower rate. Fasting for longer than the recommended time may also force the body to stimulate glucagon, increasing blood glucose levels in the body.

What other blood glucose testing options are available?

There are other ways to monitor blood glucose levels, including using a personal finger-prick style blood glucose monitor at home, or having a Glycated haemoglobin (HbA1c) blood test.

These options might be preferred for people who want to know their blood glucose levels, but choose not to have the oral glucose tolerance test, or don’t want to consume the glucose solution which can cause adverse effects, particularly in people who have undergone previous bariatric surgery.

Dr Rachel Reed explains in her article, Gestational diabetes – beyond the label that the HbA1c blood test provides an indication of what the average blood glucose levels have been over a 2 to 3 month period, but is only officially recommended for identifying pre-existing diabetes during the first trimester of pregnancy. She adds that self testing is not recommended in any medical guidelines, but remains an option for women to use themselves if they so choose.

Do I have to have a glucose tolerance test (GTT) in pregnancy?

The short answer is no. You have the right to decline or refuse any test or intervention in your pregnancy and birth at any time. But some women do report experiencing pressure or coercion to undergo testing such as the glucose tolerance test, or risk being declined care from their chosen provider such as a Midwifery Group Program (MGP).

The National Midwifery Guidelines for Consultation and Referral which inform clinical midwifery care in Australia, class diet-controlled gestational diabetes as a level B condition requiring consultation, and uncontrolled or medically controlled gestational diabetes as a level B or C, potentially requiring referral. As a result, some private practicing midwives and midwifery practices may decline prenatal care or access to homebirth to some women with a gestational diabetes diagnosis who are either medicated, or declining to medicate.

Choosing a care provider who respects your right to informed consent, is one of the best ways to feel supported in your decision making in pregnancy and postpartum.

Why is gestational diabetes increasing?

Monitoring for gestational diabetes has become a part of routine maternity care in Australia, meaning a majority of pregnant women will have their blood glucose levels checked during pregnancy.

Rising obesity, poor nutritional education, genetic predisposition and older age of mothers are all contributing to higher rates of gestational diabetes (Buckley, 2009, p 48.) But it’s important to note the diagnosis of gestational diabetes increased considerably after the diagnostic thresholds were lowered.

Dr Reed writes that despite the WHO changing their recommendations to align with IADPSG’s (International Association of the Diabetes and Pregnancy Study Groups) diagnostic parameters for gestational diabetes, they acknowledged that the quality of evidence to support this new threshold was ‘very low’, and the strength of the recommendation was ‘weak’. She states “this threshold results in up to 16% of pregnant women meeting the criteria for gestational diabetes”, up from 5% previously.

A growing number of experts are now calling for changes to the diagnostic criteria, including this recent article in the Medical Journal of Australia, which states “the definition of gestational diabetes varies considerably depending on the region where a woman lives, and considerable controversy remains on the best approach to diagnosis.”

This controversy was also summarised in a paper published in The Australian and New Zealand Journal of Obstetrics and Gynaecology, in which the author writes, “Despite the increasing numbers of women diagnosed, there is little to suggest outcomes are improved.” (Hegarty 2020).

And a Cochrane review concluded there is “insufficient evidence to suggest which strategy is best for diagnosing GDM” (Farrar et al 2017).

What alternative or natural treatment options are available for gestational diabetes?

Dietary change remains the primary treatment pathway for gestational diabetes. Generally, people diagnosed with gestational diabetes will be provided with nationally approved dietary guidelines and referred to a diabetes educator.

However, a growing number of respected nutritional professionals disagree with these guidelines, and instead promote a low GI or low-carb whole food diet.

Lily Nichols is a world-renowned registered dietitian – nutritionist and diabetes educator with a sometimes controversial view of gestational diabetes as a ‘carbohydrate intolerance in pregnancy’.

Her book ‘Real Food for Gestational Diabetes’ recommends a diet rich in real foods, avoiding processed foods, refined carbohydrates, trans fats, sugars and sweeteners, and maximising protein, healthy fats and vitamins and minerals to support a healthy pregnancy.

She also recommends 30 minutes of active movement per day during pregnancy, starting with 10 minute increments if you haven’t been exercising regularly before pregnancy. Activity uses glucose for energy, helping to naturally manage blood glucose levels.

Dr Buckley also recommends a combination of exercise and diet, and her book ‘Gentle Birth, Gentle Mothering’, reports supplementation with myo-inositol and vitamin D were of possible benefit in reducing the risk of gestational diabetes, but further high-quality evidence is needed.

Growing evidence is supporting the role gut health may have to play in managing healthy blood glucose levels too. One study found that probiotics taken during pregnancy reduced the risk of gestational diabetes by 13% and lowered the risk of having a larger baby.

What other considerations are there?

Your emotional wellbeing is just as important as your physical health as you approach your birthing time. Constant thoughts, worry and preoccupation with a diagnosis such as gestational diabetes can cause a lot of stress, and reduce your happiness and enjoyment of your pregnancy, even if the diagnosis isn’t causing any physical symptoms or complications. So it’s important to take time out for yourself, and seek support such as bodywork and mindset skills to help you relax and feel good, and connect inwards with your baby and your intuition. Because you know yourself and your body best, and to make truly informed decisions, we need to calmly gather information and practice self enquiry, to know what feels best for us.

To help with informed decision making, it can be helpful to use the BRAIN acronym, and ask your care provider or research for yourself the:

B- Benefits

R – Risks

A – Alternatives

I – Intuiton (What is your intuition telling you?)

N – Nothing or Not Now (What if we wait and see)

Michel Odent (2004) has labelled the diagnosis of ‘gestational diabetes’ as often useless, but queries if it is harmless, given a baby’s health is shaped in the womb, and a mother’s emotional state can influence the growth and development of the baby. He says the first duty of midwives, doctors and other practitioners involved in prenatal care should be to protect the emotional state of pregnant women and avoid any type of ‘nocebo’ effect.

“There is a nocebo effect whenever a health professional does more harm than good by interfering with the belief system, the imagination or the emotional state of a patient or of a pregnant woman. The nocebo effect is inherent in conventional prenatal care, which is constantly focusing on potential problems. Every visit is an opportunity to be reminded of all the risks associated with pregnancy and delivery. The vocabulary can dramatically influence the emotional state of pregnant women. The term “gestational diabetes” is a perfect example.”

Odent M, The Journal of Prenatal & Perinatal Psychology and Health (JOPPPAH) Volume 19, Number 2, Winter 2004

Where can I get more information?

You can discuss your options with your chosen care providers, consult a nutritionist who specialises in perinatal health, and you can always seek second (or third or more) opinions too. Doulas and birthworkers can also provide guidance and mentoring as you make important decisions about your care in pregnancy, birth and postpartum, and I offer private prenatal sessions which are available online or in person, to support you through this time.

Some of my favourite resources on gestational diabetes include:

Real Food for Gestational Diabetes

Gentle Birth, Gentle Mothering

Dr Sarah Wickham

The Great Birth Rebellion

Indie Birth

Rachel Reed

Michel Odent

As a doula and birth educator, my role is to support birthing families in making informed and empowered decisions about their birth. As part of this process, I want to share the latest evidence-based information and statistics on a wide range of interventions that are now so common, but not always necessary, in the Australian maternity system. And a gestational diabetes diagnosis is where I often see the cascade of interventions begin. If you’d like support with planning your informed, empowered birth, book a free meet and greet with me

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