What Is Glucose Fasting?

Early diagnosis provides the best opportunity to fight diabetes and its side effects. Glucose fasting, also known as the fasting plasma glucose test (FPG), is one of the blood tests used to determine whether a person is diabetic or pre-diabetic.

Fact

• The test is administered by taking a blood sample from the patient after they have fasted (not eaten) for at least 12 hours, hence the name "fasting" plasma glucose test.

FPG Test

• The amount of glucose left in the person's body (detected by the test) after the 12 hour fast gives an indication of how well the body is processing glucose. A normal, healthy body will have lower results on the FPG test than a person who is diabetic or pre-diabetic.

Pre-Diabetes

• Pre-diabetes is diagnosed when the FPG test results are above normal but not high enough to be considered diabetes.

Diabetes

• Diabetes is diagnosed when the test results on the FPG are well above the normal range.

Lab Values

• FPG test results of less than 100 milligrams (mg) per deciliter (dl) is considered to be normal. Results between 100 and 125 mg/dl are interpreted as pre-diabetic, while diabetes is diagnosed when the FPG test result is 126 mg/dl or greater, according to the American Diabetes Association.