Every pregnant woman is at risk of developing gestational diabetes, so it is recommended that all pregnant women are screened using a glucose tolerance blood test at 24-28 weeks’ gestation.
There are some women who are at a much higher risk and should be screened before becoming pregnant, at 12 weeks’ gestation and again at 24-28 weeks if not previously diagnosed.
High risk factors for developing gestational diabetes include:
You can read more about the risk factors for gestational diabetes for more information.
All women should be tested for gestational diabetes at weeks 24-28 gestation, which is during your second trimester. You are at a high risk of gestational diabetes if you are obese at the beginning of your pregnancy; have previously had gestational diabetes; or a close family member (i.e. mother, father, or sibling) has diabetes. If you are at a higher risk, your doctor may screen you earlier for gestational diabetes.
A pregnancy oral glucose tolerance test involves:
Typically, a blood glucose reading below 7.8mmol/L (140mg/dL) is considered to be normal.
An elevation in blood glucose levels are diagnostic at either the fasting, 1 hour or 2-hour test. You only need one test to show abnormal blood glucose readings higher than normal values, to be diagnosed with gestational diabetes.
|Fasting glucose||1 hour glucose||2 hour glucose|
|5.2 mmol/L or more||10.0mmol/L or more||8.5mmol/L or more|
|92mg/dL or more||180mg/dL or more||153mg/dL or more|
Read about how diabetes is diagnosed for more information.
Currently, there have been no studies that have defined the optimal glycaemic targets for women with gestational diabetes. Further research is required to determine optimal blood glucose targets.
Below are suggested from the Australasian Diabetes in Pregnancy Society targets for women with gestational diabetes:
Your specific blood glucose targets may be set by your doctor.
The Hb A1c targets for women who already have type 1 diabetes or type 2 diabetes, can be found in our article ‘what is the Hb A1c test’.