Fasting Blood Sugar (Glucose)
A blood test that measures the amount of glucose (sugar) in your blood after you have not eaten for several hours.
Fasting Blood Sugar (Glucose)
A blood test that measures the amount of glucose (sugar) in your blood after you have not eaten for several hours.
Also known as
- Fasting plasma glucose
- FBS
What it measures
- Blood glucose level
Why a doctor may order it
It may be part of a routine checkup to screen for prediabetes and diabetes, help find the cause of symptoms of high or low blood glucose, or monitor side effects of certain long-term medicines.
What it helps evaluate
It can help a doctor screen for and monitor prediabetes and diabetes.
Preparation
Ask your provider whether you need to fast before your glucose test.
Fasting
For a fasting glucose test you need to fast for at least eight hours. Other kinds of glucose tests don't need special preparation.
Important considerations
- Don't stop or change diabetes medicines for the test unless your doctor tells you to.
Discuss results with your doctor
Talk to a doctor about your symptoms and about what your results mean — a single result is not a diagnosis. See a doctor promptly for severe or worsening symptoms.