Explainers

Gestational Diabetes


What is Gestational Diabetes?

During the last three months of pregnancy, approximately 7 % of women have such high levels of glucose in their blood that their body cannot produce enough insulin to absorb it all.

This is known as gestational diabetes mellitus (GDM) and it can be dangerous for both mother and baby if not managed appropriately (NHS 2018).

A Growing Problem

By definition, gestational diabetes is any degree of glucose intolerance following the onset of pregnancy.

Although the general prevalence of gestational diabetes is approximately 7%, rates can vary from 1-14 %, depending on the population and the diagnostic criteria that have been used. Some researchers such as Colagiuri (2014) report a prevalence as high as 16.1%.

This reflects the fact that although gestational diabetes has been recognised as a disease for some time, diagnosis remains controversial with conflicting guidelines and treatment protocols, which may account for some of the wide variations in reported incidence (Mpondo et al. 2015).

Risk Factors for Gestational Diabetes

  • Obesity with a BMI above 30kg/m2
  • Previous large baby weighing 4.5kg or more
  • Previous gestational diabetes
  • Family history of diabetes (first-degree relative with diabetes)
  • Minority ethnic family origin with a high prevalence of diabetes

(Nursing Times 2016)

What Causes Gestational Diabetes?

The hormones produced during pregnancy can make it difficult for a woman’s body to use insulin efficiently, increasing the risk of insulin resistance.

As pregnancy places a high demand on the body, some women aren’t able to produce enough insulin to overcome this resistance. This, in turn, makes it difficult for the body to use glucose efficiently.

The result is that glucose can remain in the blood at higher levels than normal leading to gestational diabetes.

Gestational diabetes usually develops in the third trimester of pregnancy (after 28 weeks’ gestation) and then usually disappears again after the baby is born.

Whilst most women with gestational diabetes have normal pregnancies and healthy babies, the risk of some complications can be significantly increased for both mother and baby.

For example, the fetus can grow larger than normal, causing problems during delivery and increasing the chances of caesarean section. The incidence of premature birth, miscarriage or stillbirth may also be higher.

Post-delivery, the baby is also more likely to be overweight or have diabetes later in life (Nursing Times 2016).

Risk Factors for Gestational Diabetes Mellitus - Ausmed

Managing Maternal Obesity

It’s well known that women can significantly reduce their risk of developing gestational diabetes by managing their weight, keeping active and eating a healthy diet.

Wang et al. (2015), suggests that a higher body mass index (BMI) before or during the first trimester of pregnancy coupled with excessive gestational weight gain (GWG) are both considered early markers of gestational diabetes.

Women with both these factors are known to increase their risk of developing gestational diabetes by 2.2-5.9-fold.

It’s also much more likely that both mothers and their babies will remain overweight a decade or more after birth. So, as Wang et.al suggests, a vicious cycle of excessive gestational weight gain, obesity and gestational diabetes can quickly develop.

The recommendations for further action are clear. Pregnancy-related weight problems must be addressed and given adequate attention.

Kampmann, et al. (2015) reinforces Wang’s urging to pay more attention to the dramatic increase in the prevalence of obesity in women of childbearing age. In recent years there has been a sharp increase in the incidence of overweight and obese women and a consequent rise in complications during pregnancy and birth.

Not only does this put both mother and baby at risk of serious long-term consequences, the clinical management of obese pregnant women and women with gestational diabetes also puts a significant additional strain on the healthcare system.

Gestational Diabetes and Warm Weather

Less well known are the risks of developing gestational diabetes in warm weather.

Several researchers have noted that more cases occur in the summer months, suggesting that the condition may be seasonal, or that misdiagnosis could be more likely during warm months of the year (Ford 2018).

Vasileiou (2017), also found that during the summer months average non-fasting blood sugar values were higher compared to winter, while fasting sugar levels were not.

One reason for this may be due to an increase in blood flow in warm weather that may diminish sugar extraction from blood to tissue.

Similar studies exploring the link between warmer weather also found that glucose levels tended to increase when it was hotter and that the summer months were linked to a 51% increase in the diagnosis of gestational diabetes (Nursing Times 2016).

Clearly, there is a need here to develop better screening programs to ensure that pregnant women are properly diagnosed and only receive treatment when their blood sugar levels can pose a danger to themselves and their baby. The aim is to avoid any unnecessary treatment and distress during pregnancy (Vasileiou 2017).

Complications Following Gestational Diabetes

Gestational diabetes mellitus is the most common cause of diabetes during pregnancy and as Mpondo et al. (2015) suggests could account for up to 90 % of pregnancies complicated by diabetes.

Longer term this could leave mothers with a 40-60 % chance of developing diabetes mellitus over the 5-10 years following pregnancy. Other researchers suggest this figure is lower at 30% but the risks are none the less high (NHS UK 2018).

Additional complications include the development of hypertension and ischemic heart disease at a relatively young age compared with women without a previous diagnosis of gestational diabetes (Daly et.al 2018).

Should Screening be More Intensive?

Traditionally screening takes place during the 28th week of pregnancy, but recent studies suggest that diabetes-related changes to the fetus may have already occurred by then (Nursing Times 2016).

Whilst no differences were seen as early as 20 weeks’ gestation, there are calls for screening to start at 24 weeks, with increased monitoring of women with known risk factors from as early as the first trimester.

Daly et al. (2018), suggests that mothers with gestational diabetes are not only at greater risk of developing type 2 diabetes in the first year following delivery but for up to 25 years following birth.

Yet following delivery, less than 60% of women receive follow-up screening in the first year and less than 40% by the second year.

The message here is clear. A diagnosis of gestational diabetes mellitus can significantly increase the risk of further physical health problems for the mother, fetus, and child.

Alongside this are the additional negative effects on maternal mental health and diminished quality of life (Marchetti et al. 2017).

Is a change in practice needed?

Kampmann et al. (2015) suggests that it is. Recommending that the way forward must also include greater interventions in the form of exercise, weight loss and a healthy diet.

With these additional support measures, there might then be an opportunity to break the vicious circle that contributes to the epidemic of obesity, insulin resistance and type 2 diabetes.

For More on Gestational Diabetes, view the Online Course:

Learning Outcomes:
1. Explain the pathophysiology of gestational diabetes (GDM)
2. Describe the risk factors and diagnostic criteria
3. Identify clinical targets and general management principles for antenatal, labour and postpartum care

View Course! →

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