The Fasting Blood Sugar test is used to measure the amount of glucose (sugar) present in your blood after fasting for a whole night or 8 hours. This test helps in treating individuals with diabetes. The Fasting Blood Sugar test is the most commonly prescribed test for diabetes and it is the simplest and fastest test. Postprandial means after a meal. This test is done to see how your body responds to sugar and starch after you eat a meal. As you digest the food in your stomach blood glucose or blood sugar levels rise sharply. In response your pancreas releases insulin to help move these sugars from the blood into the cells of muscles and other tissues to be used for fuel. Within 2 hours of eating your insulin and blood glucose levels should return to normal. If your blood glucose levels remain high you may have diabetes.