Fasting Plasma Glucose Test

19 Jun

Posted by admin as Uncategorized

The fasting plasma glucose (FPG) test, also known as the fasting blood sugar test, measures blood glucose (blood sugar) levels and is used to diagnose diabetes in non-pregnant adults. Relatively simple and inexpensive, the test exposes problems with insulin functioning. Prolonged fasting triggers several hormones including a hormone called glucagon. It is produced by the pancreas and causes the liver to release glucose into the bloodstream. If a person doesn’t have diabetes, his or her body reacts by producing insulin, which prevents hyperglycemia (high blood sugar). However, if one’s body cannot generate enough insulin, fasting blood sugar levels will stay high.

The fasting plasma glucose test is performed after a person has fasted for at least 8 hours. A sample of blood is taken from a vein in the arm. If the blood glucose level is greater than or equal to 126 mg/dl, the person is retested and, if the results are consistent, diagnosed with diabetes. (Until a few years ago, the diagnostic cut-off point was 140 mg/dl, but the ADA lowered it because research has shown that even people with fasting plasma glucose levels between 126 mg/dl and 140 mg/dl tend to develop the medical complications of diabetes.)

What Do the Results of the Blood Glucose Test Mean?

Normal fasting blood glucose is between 70 and 100 milligrams per deciliter or mg/dL for people who do not have diabetes. The standard diagnosis of diabetes is made when two separate blood tests show that your fasting blood glucose level is greater than or equal to 126 mg/dL. However, if you have normal fasting blood glucose, but you have risk factors for diabetes or symptoms of diabetes and your fasting blood glucose is normal, your doctor may decide to do a glucose tolerance test (see below) to be sure that you do not have diabetes. Some people have a normal fasting blood glucose reading, but their blood glucose rapidly rises as they eat. These people may have glucose intolerance. If their blood glucose levels are high enough, they may be diagnosed with diabetes.

How is this test performed?

The American Diabetes Association recommends that the FPG test be administered in the morning because afternoon tests tend to give lower readings. It is also usually more convenient to take the test in the morning because you must fast for 12 to 14 hours beforehand. The test consists of a simple blood draw, which is sent to your doctor’s lab for analysis. How frequently should this test be performed? Up to two times for diagnostic purposes, or as required when monitoring a treatment regime.

Understanding the Results of the Fasting Plasma Glucose Test

Doctors interpret test results by looking at glucose levels in the blood. Diagnosis categories include the following, measured in milligrams per deciliter (mg/dL): In the fasting plasma glucose test, 70 mg/dL to 99 mg/dL is considered within the normal range. A reading of 100 mg/dL to126 mg/dL suggests prediabetes, indicating an increased risk in developing full-blown diabetes.A reading above 126 mg/dL is the threshold at which diabetes is diagnosed. Blood glucose levels lower than 70 mg/dL imply an episode of hypoglycemia, in which blood sugar is dangerously low.

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