Perinatal Centre

If risk factors for gestational diabetes are noted at your booking appointment, you will need an OGTT – Oral Glucose Tolerance Test.

What are the risk factors?

If you have a previous history of gestational diabetes, this test will be offered at 16 weeks. If this test is negative it will be repeated again at 24 -28 weeks.

If we note other risk factors, the test will be completed between 24-28 weeks gestation. These include:

• A BMI of 30 or above

• Maternal age of 40 or more

• First degree relative with type 1 or type 2 diabetes

• A previous baby weighing 4.5kg or more

• A history of PCOS

If any concerns arise through routine checks during your pregnancy you will also be offered testing. 

How do I prepare for the OGTT?

An Oral Glucose Tolerance Test consists of three blood tests taken before and after a glucose drink.

• The first blood test finds your baseline glucose level.

• You will then be given a glucose drink.

• After 1 hour a further blood test will be taken.

• After another hour the final blood test is taken to complete the test.

For the test to be effective, you need to sit down between the blood tests, and you are required to stay in the hospital building for the duration of the test. If the test has to be abandoned for any reason such as vomiting, the test will be rebooked for you.

What if my test is positive?

Women with gestational diabetes are deemed as having a high risk pregnancy and require closer monitoring until the delivery of your baby. If your OGTT is positive, a diagnosis of gestational diabetes will be confirmed and you will contacted by our diabetes team for further care  during your pregnancy. Treatment for gestational diabetes starts with changes to your lifestyle, following a healthy eating plan and exercise with support from our multidisciplinary team.  We will closely monitor your blood glucose levels and, if it’s needed, further treatment will be discussed with you.

What happens after my baby is born?

After your baby is born, we recommend that you book another OGTT with your GP at your 6-week check-up.  This GTT will ensure that blood sugars have returned to pre-pregnancy levels.