Glucose is a type of sugar that serves as the main source of energy used by the body. Insulin is a hormone that helps the body's cells to use the glucose. Excess or shortage of insulin in the body causes an imbalance of the blood glucose in the body, leading to its severe drop or drastic increase in the blood. Blood glucose levels that remain high over time can cause damage to the eyes, kidneys, nerves and blood vessels. Chronic low glucose levels can lead to brain and nerve damage.
Fasting blood sugar (FBS): It measures blood sugar levels either after 8-12 hrs. or overnight fast and it is often the first test done to check for pre-diabetes and diabetes. Blood sugar levels outside the normal range may be an indicator of a medical condition. Fasting means refraining from eating or drinking any liquids other than water for eight hours. It is used as a test for diabetes. After fasting, a carbohydrate metabolism test is conducted which measures blood glucose levels.
A Postprandial Plasma Glucose Test: is a blood test that measures blood glucose levels following a meal containing a set amount of carbohydrate. Postprandial Plasma Glucose Tests show how tolerant the body is to glucose. Normally, blood glucose levels increase slightly after eating. This increase causes the pancreas to release insulin, which assists the body in removing glucose from the blood and storing it for energy. People with diabetes may not produce or respond properly to insulin, which causes their blood glucose to remain elevated. Blood glucose levels that remain high over time can damage the eyes, kidneys, nerves, and blood vessels. 2-hour postprandial blood test measures blood glucose exactly 2 hours after eating a meal, timed from the start of the meal. By this point blood sugar has usually gone back down in healthy people, but it may still be elevated in people with diabetes. Thus, it serves as a test of whether a person may have diabetes, or of whether a person who has diabetes is successfully controlling their blood sugar.