Diabetes In Pregnancy – Reviewing The Review

What is diabetes in pregnancy / gestational diabetes?

Diabetes in pregnancy or gestational diabetes is described as high blood sugar in pregnancy (that does not exist before pregnancy and goes away after pregnancy). Unfortunately, no one can agree on the right blood sugar levels for pregnant women. You get tested in one hospital and you might end up with a positive diagnosis… go to another hospital and your test is negative. Go to the same hospital and get tested on a different day and/or time of day and your diabetes in pregnancy test may come back differently.

I had a client in New Zealand who got six tests done, all showing different results! She was able to successfully stand her ground and was not labelled with gestational diabetes and her antenatal and birth care were not affected.

In the Screening, Diagnosis and Management of Gestational Diabetes In New Zealand: A Clinical Practice Guide (DRAFT Version) by Auckland University, it’s claimed that the incidence of diagnosis of diabetes in pregnancy has been increasing. However, “The increased rates of gestational diabetes over the last two years may reflect changes in local policy for the diagnosis of gestational diabetes”. Change the criteria for pregnancy blood sugar levels and you’ll suddenly get a surge in diagnoses.

I shall be referring to this report throughout this article.

What does the research say about gestational diabetes?

The ideal situation would be to detect true diabetes early on in pregnancy so that women are supported and cared for appropriately. Unfortunately though, the medical community haven’t produced sound research into this area.

“Screening protocols, together with the appropriate subsequent management, can affect health outcomes and ideally should be evaluated with randomised controlled trials. No randomised controlled trials were identified.”

I’m not sure how they can claim managing pregnancies labelled with gestational diabetes helps outcomes when there is no evidence to support it.

Randomised controlled trials are the gold standard of scientific enquiry, for some reason no one sees fit to produce research that will stop thousands of healthy women being misdiagnosed later in pregnancy;

“A total of six systemic reviews and 58 additional observational studies were identified. Overall the quality of the evidence is very low”.

“No published randomised controlled trial evidence was found.”

“The study did not have a control group so it was unable to determine whether screening early in pregnancy was associated with beneficial outcomes for pregnant women.”

It seems they like the idea of managing women with gestational diabetes tests and interventions, but they can’t find the valuable evidence to support it.

One study tested women in their first round of antenatal blood tests (that is, in the first trimester), and were then offered a glucose tolerance test before 20 weeks gestation. They found that 0.6% of the women tested “probably” had undiagnosed diabetes. The early blood test was found to be a great way of discovering true diabetes but they failed to carry on the research to find out if it had any impact on pregnancy or birth outcomes.

The big question is, if you set the criteria so that a group of people are labelled as having gestational diabetes, is this going to have an affect on outcomes? If it doesn’t have a positive affect (that is, if the diagnosis is not saving lives or preventing injury), is it worth testing for? Would it be better to scrap the tests and have conversations with women about healthy eating and exercise since that seems to be what makes the most difference to most women?

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What causes gestational diabetes?

According to Dr Michel Odent, diabetes in pregnancy is a normal response to the unborn baby’s needs. The placenta mediates between the mother and baby, altering the mother’s hormone balance to provide more, or less sugar, to the baby. If the baby needs sugar, the mother may have ‘too much’ sugar in her blood which makes it look like she has diabetes. Any excess sugar is either reabsorbed by the mother or excreted in her urine.  As an unborn baby grows bigger they will naturally need more sugar. This is why gestational diabetes is rarely diagnosed before 28 weeks.

There are some women with undiagnosed true diabetes (either Type I or Type II Diabetes). With Type I diabetes, insulin is not produced and with Type II diabetes the body doesn’t respond to insulin. For some pregnant women diabetes may have been undetected before pregnancy (or pregnancy has tipped her into Type II Diabetes). This type of true diabetes is dangerous for the baby as it can cause problems with development and put the baby at risk of miscarriage and blood sugar issues during birth and the first few days of life. https://www.nhs.uk/conditions/pregnancy-and-baby/diabetes-pregnant/

Women with gestational diabetes, on the other hand, are still able to adjust their insulin levels. Their body still responds to insulin and they generally don’t experience any symptoms of Type I or Type II diabetes.


Who’s at risk of diabetes in pregnancy?

The medical community have named some key characteristics of women at greater risk of diabetes in pregnancy;

  • Increasing maternal age
  • Family history of diabetes
  • High risk ethnic group
  • Elevated body mass index (interestingly though “Obesity did not influence outcomes. There were no observed effects on birth trauma”).
  • Previous macrosomic infant (a baby weighing over 8lb 13oz or 4000g)
  • Previous history of impaired glucose intolerance
  • Women with polycystic ovarian syndrome
  • Known cardiovascular disease, persistent hypertension, elevated triglycerides/cholesterol
  • Acanthosis nigricans (a skin condition characterized by areas of dark, velvety discoloration in body folds and creases, that typically occur in people who are obese or have diabetes)
  • Long term use of steroids/antipsychotic medication
  • Physical inactivity/sedentary lifestyle

You might look at this list and think you’re not at risk of diabetes in pregnancy. Unfortunately, you could still get the gestational diabetes label. Studies, reported in the Auckland University document, show that;

“Significantly more women were diagnosed with gestational diabetes in the universal screening group than the risk factor screening group. Infants of mothers born in the risk factor group were born earlier but the difference is unlikely to be of clinical significance. Although women who were routinely screened by 50g glucose challenge test were more likely to be diagnosed with gestational diabetes than those screened by their risk factors, effects of subsequent management on health outcome are unclear.”

In other words, you are more likely to be diagnosed with gestational diabetes when you’re not at risk of gestational diabetes. You can start to see why Dr Michel Odent and medical journalist Henci Goer don’t believe there is gestational diabetes at all.

“Selective screening would lead to missing one-third of the women with gestational diabetes who, even without risk factors, had more events [it’s unclear what they mean by this] than women without gestational diabetes… It was suggested that women with gestational diabetes, but no risk factors, would have a good prognosis and therefore missing their diagnosis would be of minimal consequence.”

Heavier bodies require more sugars to fuel them, so, if you set particular criteria for everyone, naturally a whole group will fail and look like they have diabetes in pregnancy. It’s also possible to set the criteria so that whole communities of people will be labelled. If you’re a community with a high carbohydrate diet, you’ll fail the gestational diabetes test quite frequently, as is the case with Indian women.

Some babies grow big even when there is no evidence of gestational diabetes. That’s just how they grow. Research has shown that when the medical team are expecting a big baby, more interventions and poor outcomes are reported. Not knowing there is a big baby on the way means you’re less likely to have problems in birth. It’s not the size of the baby that’s the problem, it’s the expectation of problems that is. When a baby is in the right position and the mother is able to move freely, most babies can birth themselves. The medical team are there in case of emergencies, but that doesn’t mean they should be managing the birth so hard that the emergency then occurs.

The research reviewed in the Auckland University report shows

“the available evidence has substantive heterogeneity [diversity] with serious flaws in study design and methodology. There was insufficient evidence to draw any conclusions on optimal timing and mode of delivery in women with gestational diabetes. The Guideline Team therefore made good practice points based on the available data”.

Translated, this means there is no research to support interventions but, talking amongst ourselves, we’re going to carry on doing what we want to do anyway.



Testing for diabetes in pregnancy

“The Guideline Development Team decided that women considered at high risk for gestational diabetes … should be offered the one-step diagnostic oral glucose tolerance test at 24 to 28 weeks gestation. All other women should be offered screening for gestational diabetes with the 1 hour, 50g oral glucose challenge test followed by oral glucose tolerance test (if the challenge tested positive) known as a two-step strategy. The Guideline Development Team (noted that women should be informed that the glucose challenge test can be falsely normal in approximately 20% of women with gestational diabetes. Also, that if the screening test is elevated, they will still be asked to go for an oral glucose tolerance test to diagnose gestational diabetes… As there is a lack of good quality evidence for the optimal screening strategy at 24 to 28 weeks gestation the Guideline Development Team were only able to make Good Practice Points”.

Despite the claim that undiagnosed gestational diabetes in low risk groups doesn’t make much difference, the medical team has still decided to test everyone anyway. Despite the lack of science supporting what they are doing, they’re going to carry on doing it to pregnant women anyway.

I had a client who was super fit and healthy, ate really well, was slim and enjoying a great pregnancy but was tested for gestational diabetes because she had Asian heritage. Her label of being an ethnic minority caused her to undergo a test that completely changed the course of her pregnancy and management of birth. Her stress levels went right up, her trust in her body dropped down low, her anxiety about her pregnancy increased and she had to make changes to her birth. If she had been white she would never have been offered the test. Just like her white counterparts, I imagine she would have had no idea about her blood sugar levels and experienced pregnancy and birth as everyone else does… that is “missing their diagnosis would be of minimal consequence.”

It’s important to remember that the NHS constitution, upheld by law, allows you to accept or refuse care offered. If you don’t want the test, you don’t have to have the test, and your decision has to be respected by your care provider… by law. Here’s an article about that.


Gestational diabetes symptoms

Unlike true diabetes, gestational diabetes / diabetes in pregnancy, generally has no symptoms. You might be enjoying your pregnancy one minute and the next you’re full of anxiety and stress because you’re having to do finger prick blood tests four or five times a day and worried for the health of yourself and your unborn baby.

Your body is not broken. You are responding to your baby’s needs for nutrition. Most of my clients who are diagnosed with diabetes in pregnancy report healthy blood sugar levels when they test themselves each day. Often there’s a small blood sugar spike in the morning because their baby is asking for sugar when they haven’t received enough during the night. Having a small snack by your bed for when you wake in the night will help you and baby and hopefully help you get back to sleep too. This is true for all pregnant women waking in the night.

Signs of gestational diabetes may include:

  • Increased thirst (also normal in pregnancy)
  • Dry mouth (also normal in pregnancy)
  • Needing to pee more often (also normal in pregnancy)
  • Tiredness (also normal in pregnancy)


Glucose test pregnancy

The general test for diabetes in pregnancy involves fasting over night, then drinking a very, very sweet drink, after which you must sit still for 1 to 2 hours (depending on whether you’re in the risk category or not). After this time you provide a urine sample to find out how much sugar you have excreted. It’s not pleasant, not least because that much sweet fluid on an empty stomach is quite revolting, but because any pregnant woman expected to sit still is quite frankly cruel and not reflective of normal life. Sitting still after ingesting high amounts of sugar, while your baby dances on your bladder, really isn’t cool. No other groups of people are expected to undergo this for a diabetes test, only pregnant women.

Sadly, the best test for diabetes isn’t effective after 24 weeks in pregnancy. It’s the HbA1c blood test which can determine what your blood sugars have been over the past three months. Highly useful if you use it early on in pregnancy or before pregnancy to discover true diabetes.

“Another study evaluated HbA1c as a screening test between 24 and 28 weeks for gestational diabetes mellitus in a high risk population in India (Agarwal et al 2005). HbA1c would eliminate the need for oral glucose tolerance test in 25% of this population of whom 27% would be misclassified. At any HbA1c threshold with an acceptable sensitivity, the false positive rate remained high making it necessary for too many healthy women to undergo the confirmatory oral glucose tolerance test. They concluded that HbA1c was a poor test to screen for gestational diabetes in later pregnancy”

Like I said earlier, you have a test one day and it looks like you have diabetes in pregnancy, but go back another day, when your baby isn’t asking for so much sugar and you get a different reading. Your baby’s needs will skew test results.

“There was a wide range in diagnostic accuracy”

“Differences in prevalence associated with different diagnostic criteria were identified in 5 observational studies”


Gestational diabetes diet

Studies have shown that a gestational diabetes diet can help maintain blood sugar levels at an ‘acceptable’ level in many women when grouped with exercise. It has been noted that babies are smaller at birth and were less likely to have jaundice and less likely to get shoulder dystocia than those who did not change their diet. The risk of pre-eclampsia was reduced in women maintaining a gestational diabetes diet but their risk of induction was higher (if you’re inducing women before 40 weeks then of course inductions will be higher).

I find medically imposed pregnancy diets very interesting. Recommendations change frequently. It wasn’t long ago that maternity professionals told pregnant women, with gestational diabetes, to cut right down on carbohydrates (sugars). I had many clients in New Zealand whose babies stopped growing around 34 weeks. Frequently, clients of mine in New Zealand and the UK, with gestational diabetes, carry smaller for age babies. Why? Because that’s what happens to babies when you cut out an important food group.

The recommendation now is reduce carbohydrates but not too much. The report from Auckland University suggests 1800kcal/day with 175g of carbohydrates. I find this crazy since that’s the same nutritional recommendation of a woman, who’s not growing a whole person, to maintain weight LOSS. The recommended amount of carbohydrates is less than for non-pregnant diabetics! Pregnant women should not be given the same dietary advice as non-pregnant women. Their physiology is different, their nutritional needs are different.

Pregnant women are eating for two people (even though one is pretty small, they are still, literally being made rather than maintained), a placenta, 40-50% extra blood volume, the extra energy required to carry all that extra weight and develop a human being, all whilst maintaining work performance, getting enough exercise and running around after other children (if this isn’t their first child).

Maintaining a healthy diet and exercising is the best way to achieve a healthy pregnancy. Some women will put weight on in pregnancy for apparently no reason (it’s usually because the hormone oxytocin makes you absorb more nutrition). Fat shaming mothers and expecting them to diet is really not cool, not healthy and totally pointless.


Gestational diabetes and birth outcomes

Simply put, there’s not enough quality data to support inductions or planned caesareans for women with gestational diabetes. Women who manage their blood sugar levels well seem to be less likely to have larger babies, less likely to have a baby with jaundice post birth and babies are less likely to get shoulder dystocia during birth.

A birth where the baby is expected to be small or average will be managed differently to a birth where the baby is expected to be large. The research studies likely didn’t account for this.

There is no research supporting induction of women, with well managed blood sugar levels, before 40 weeks. There’s not enough research to support 40 weeks being the cut off point for pregnancy. There is no science stopping you from continuing your pregnancy past 40 weeks if your blood sugars are well managed (and there are no other indications for induction. Large for gestational age not being one of them)… you are just the same as everyone else.

“Treatment decisions should not be based solely on foetal ultrasound.”

The main focus of of worry about gestational diabetes is the baby being too big to be born vaginally. There is nothing wrong with a big baby in itself. Some babies just grow big. The issue with any baby is whether they are in the right position or not to be born easily. That’s not about the size of the baby, it’s about getting ready for birth during pregnancy and being able to move freely during birth. If you induce a birth before baby is in the right position, you’ll likely end up with more interventions including instrumental delivery or a cesarean.



Generally, if you would like to come away more confused as to why recommendations are made have a read of this report. It’s very dry reading if you’re not medically trained but there is a Glossary on page 117. Please do let me know if I’ve misinterpreted some of the data. I have read the review a couple of times but it gets pretty confusing when the research is saying one thing (or not) and the Good Practice Team are saying something different. Good luck!

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