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09th Aug 2023

All you need to know about gestational diabetes – from signs to diagnosis


Gestational diabetes affects 5-10% of Irish women.

If this condition is left undetected and uncontrolled, it can lead to a number of complications for the mother and baby.

So, here’s everything you need to know about gestational diabetes, from signs to look out to diagnosis and treatment.

So, what is gestational diabetes?

Diabetes is caused by having too much glucose, or sugar, in the blood. The amount of glucose in the blood is controlled by the hormone insulin, which is created by the pancreas.

While you’re eating, your digestive system breaks down any food and the nutrients get absorbed into your bloodstream.

Insulin is normally created to take any glucose out of your blood and move it into your cells, where the glucose is then broken down to produce energy.

During pregnancy, the body produces a number of hormones – like oestrogen and progesterone – that make your body insulin-resistant.

This means that the cells won’t respond as well to insulin, and the level of glucose within the mom-to-be’s blood remains high.

The reason behind the hormonal effect is so that the extra glucose and nutrients in the blood pass on to the unborn baby, so it can grow.

However, to be able to cope with the increased amount of glucose in the bloodstream, the body should be creating an increased amount of insulin.

But since some women have slightly elevated levels of glucose in their blood, the body cannot produce enough insulin to transport it all.

And what are the symptoms?

Gestational diabetes is usually diagnosed during routine screenings  – and before it causes any symptoms or issues. However, it often won’t cause any symptoms at all.

High blood glucose, or hyperglycaemia, can cause some symptoms, including:

  • being thirsty
  • having a dry mouth
  • needing to urinate frequently
  • tiredness
  • recurrent infections, such as thrush (a yeast infection)
  • blurred vision

What are the risk factors?

According to the HSE, you may be at risk of gestational diabetes if:

  • you have previously had a baby who weighed 4.5kg (10lbs) or more at birth
  • you had gestational diabetes in a previous pregnancy
  • you have a family history of diabetes – for example, one of your parents has diabetes
  • your family origins are South Asian (specifically India, Pakistan or Bangladesh), black Caribbean or Middle Eastern (specifically Saudi Arabia, United Arab Emirates, Iraq, Jordan, Syria, Oman, Qatar, Kuwait, Lebanon or Egypt)

What are the complications of gestational diabetes?

There are a number of complications of gestational diabetes, both of the mum and baby.

But the HSE says that if your blood glucose levels have been effectively controlled throughout pregnancy, the risks decrease.

Gestational diabetes may increase the risk of:

  • pre-eclampsia, a condition that causes high blood pressure in pregnant women
  • placental abruption, when the placenta starts to come away from the wall of the womb
  • needing to induce labour
  • premature birth
  • macrosomia
  • trauma during the birth to yourself and your baby
  • neonatal hypoglycaemia, when your newborn baby has low blood glucose, which can cause poor feeding, blue-tinged skin and irritability

There’s also a risk that after pregnancy, you are more likely to develop type 2 diabetes than a woman who did not have gestational diabetes.

Type 2 diabetes is when the body doesn’t produce enough insulin, or the body’s cells do not react with the insulin.

According to the HSE, your baby may be at a greater risk of developing diabetes or obesity at a later stage in life.

You are also at an increased risk of having gestational diabetes in any future pregnancies.

You can find a full list of complications here

How do you diagnose gestational diabetes?

According to the HSE, every pregnant woman should be offered a screening test for gestational diabetes.

The screening would usually take place at your booking appointment, around weeks 8-12 of your pregnancy.

This is when your GP or midwife would find out if you are at risk of gestational diabetes. If any of the risk factors apply to you, you will be offered a test for gestational diabetes.

The testing involves the use of an oral glucose tolerance test (OGTT) or a random blood glucose test.

The first one, the OGTT, will involve a sample of your blood being tested, then you being given a glucose drink. Further samples will be taken every half an hour for two hours to see how your body is dealing with the glucose.

If you don’t have gestational diabetes, you could possibly be asked to return for another blood test around weeks 24-28.

If you do have gestational diabetes, you will be advised on how to control and keep an eye on your blood glucose levels.

Meanwhile, a random glucose blood test involves taking a sample of blood from a vein in your arm. It may involve having one or more samples taken and tested to see if your blood glucose levels are as expected.

How do you treat gestational diabetes?

If you are diagnosed with gestational diabetes, your GP or midwife will advise you on how to monitor and control your blood glucose levels.

The HSE notes that at least eight out of ten women are able to control their gestational diabetes through increasing the amount of exercise they do and a change in diet. One or two women out of 10 would need medication.