Blood sugar, or blood glucose, is the result of carbohydrate metabolism. The sugar is the food for all the cells of the human body; it powers the heart, other organs and, in particular, the brain. If the brain lacks adequate sugar, brain damage and even death can result. But too much sugar in the blood isn't healthy either; it can cause diabetes. The body keeps the blood sugar within a narrow range for optimum health. When carbohydrates are eaten, the starches are digested within the small intestine and then absorbed into the bloodstream. As a result, the blood sugar increases.
Insulin and Blood Sugar
Blood sugar is controlled by two hormones: insulin and glucagon. If the blood sugar rises, receptors in the pancreas are triggered by the higher sugar level. The pancreas then secretes insulin, which helps the tissues of the body to absorb the sugar, or glucose. Without insulin, these tissues would not be able to absorb the glucose. Only the brain and liver do not require insulin for glucose absorption.
Insulin and Glucagon
Insulin has another important function. It stimulates the liver to store glucose in the form of glycogen, creating a storage bank for future use. When the blood sugar begins to fall -- perhaps at the end of the day when you are hungry for dinner -- the pancreas releases glucagon. The glucagon causes stored sugar, which is known as glycogen, to be released from the liver to bring the blood sugar level higher. Insulin also is secreted if the sugar level gets too high, and the cycle of insulin and glucagon secretion will repeat as necessary to keep the blood sugar stable.
Another Factor in Blood Sugar
There is another mechanism in the body that affects blood sugar. In the condition known as the "flight or fight" response, a neurotransmitter called adrenalin is released to override the normal mechanisms of blood sugar control. Adrenalin causes an increase in the body's metabolism, which means more fuel is required. The adrenalin overrides the usual blood sugar regulatory mechanism and causes glycogen to be released, raising the blood sugar temporarily.
The Bottom Line
Not too high, not too low -- the human body needs the blood sugar to be just right. According to Dr. James Norman, an endocrinologist, the blood glucose should be between 70 mg/dl and 110 mg/dl. Mg/dl means milligrams of glucose in 100 milliliters of blood. The blood sugar should not go above 180 mg/dl even after eating; if it does, you may have diabetes and should consult a health care professional.
