Glucose is the main form of energy for the body and travels in the bloodstream. The body requires a certain amount of glucose to function properly, but having too much or too little glucose in the blood is harmful and can lead to many complications. Therefore, several types of tests exist to monitor blood glucose levels.
Fasting Blood Glucose Test
The fasting blood glucose test (FBG) is designed to provide an at-the-moment sample of blood glucose levels. It is important in diagnosing diabetes and pre-diabetes as well as hypoglycemia (lower than normal blood sugar levels). For accurate results, an individual is required to fast, no food or drink, for at least eight hours before the blood sample is drawn. The test requires only a small drop of blood and is often measured during routine blood draws. The results are given as a whole number in milligrams per deciliter of blood. According to the American Diabetes Association, normal fasting blood glucose levels are 70 to 99 milligrams per deciliter of blood.
Hemoglobin A1c
The hemoglobin A1c test measures an individual's average blood glucose levels for the preceding two to three months. It's primarily used as a tool to assess overall glucose control in individuals with diabetes. However, in December 2009, the American Diabetes Association recommended the A1c test as a diagnostic and risk assessment tool for diabetes and pre-diabetes, a condition in which blood sugar levels are higher than normal, but not high enough to be considered diabetes. Hemoglobin A1c test results are given as a percentage in the range of 3 percent to 14 percent, with normal values below 6 percent for individuals without diabetes. A great benefit of this test is that it requires only a drop of blood from the finger from an individual who does not have to be fasting.
Random Blood Sugar Test
Like the fasting glucose test, this test provides an at-the-moment measure of blood glucose levels, but it is generally used as a way to measure blood glucose levels in diabetic individuals or those with high or low blood sugar diseases, not as a diagnostic test. The test requires only a small drop of blood placed on a testing strip of a glucose meter and provides results within seconds. The results are given as a whole number and can vary widely depending on if the person has recently eaten. This test is designed primarily for individuals with diabetes as a quick and easy way to measure blood glucose levels to determine insulin dosing, carbohydrate needs and glucose control.
Oral Glucose Tolerance Test
The oral glucose tolerance test (OGTT) is used as a diagnostic tool for diabetes and gestational diabetes. The test is generally administered after the fasting glucose test to confirm a diagnosis of diabetes. For the test, the individual is required to be fasting and is administered a liquid solution containing 50, 75 or 100 grams of glucose. The individual's blood glucose levels are then checked one and two hours after ingesting the liquid with a blood glucose meter. In testing for gestational diabetes, blood sugar levels are tested every hour for three hours.
