Patients are required to make an appointment for a GTT test, and must fast overnight (8 - 12 hours) prior to the test.

This test is available at all Austin Pathology Collection Centres.

The test should not be performed if the patient is under stress, e.g. post recent AMI, surgery, or when they are ill.

Please note: At present, we are following RANZCOG RECOMMENDATIONS for the SCREENING AND DIAGNOSIS OF GESTATIONAL DIABETES.

The relevant recommendations are listed below:

• If a woman is currently positive for COVID-19, symptomatic or in isolation awaiting test results, GDM testing should be delayed until after that period.
• For patients with identifiable risk factors for GDM, an HbA1c should be performed with antenatal serology. A cutoff of 5.9% should be considered diagnostic of GDM.
• Women with previous GDM should either have a fasting blood glucose level tested at 24-28 weeks gestation or be considered as having GDM and commence home BGM from 28 weeks gestation
• All other women should have a fasting blood glucose at 24-28 weeks with GDM diagnosed if glucose is >=5.1mmol/L
• Postnatal GTT should be deferred until the resolution of the pandemic, unless post-natal blood glucose levels are elevated

This advice is not exhaustive and does not attempt to cover every scenario. Furthermore, individual clinical circumstances vary and all clinicians should apply appropriate discretion.

ALL SPECIMENS MUST BE LABELLED WITH THE COLLECTION TIME.

Note on the request form if the patient is pregnant or not pregnant.

1.  Collect 2 mL blood into a Fluoride Oxalate tube  (plus 5 ml blood into a serum tube if insulin required)
2.  The patient is then given 75 g glucose to drink. Record the time of consumption of the drink.
3.  At one and two hours after completion of the glucose drink , collect 2 mL blood into a Fluoride-EDTA tube (plus 5 ml blood into a serum tube if insulin required)

The procedure will last approximately 2 hours, during which time the patient should remain fasting (no eating, smoking or chewing gum) and at rest.

Add ons for this test cannot be performed.