A fasting plasma glucose test, also known as a fasting glucose test (FGT), is a test that can be used to help diagnose diabetes or pre-diabetes
The test is a simple blood test taken after several hours of fasting.
How a fasting glucose test is performed
A fasting glucose test will be performed in the morning as this provides the body with adequate time to fast.
The NHS advises people who are having a fasting glucose test not to eat or drink anything except water for 8 to 10 hours before the test is performed.
The test requires a blood sample to be taken from the patients arm.
Fasting glucose test results
The World Health Organisations defines the following fasting glucose test results:
- Normal: Below 5.5 mmol/l (100 mg/dl)
- Impaired fasting glucose: Between 5.5 and 6.9 mmol/l (between 100 mg/dl and 125 mg/dl)
- Diabetic: 7.0 mmol/l and above (126 mg/dl and above) 
Impaired fasting glycemia is a form of pre-diabetes.
Read more on impaired fasting glycemia