Blood Glucose

A blood glucose test measures the amount of a type of sugar, called glucose, in your blood. Glucose comes from carbohydrate foods. It is the main source of energy used by the body. Insulin is a hormone that helps your body's cells use the glucose. Insulin is produced in the pancreas and released into the blood when the amount of glucose in the blood rises.

Normally, your blood glucose levels increase slightly after you eat. This increase causes your pancreas to release insulin so that your blood glucose levels do not get too high. Blood glucose levels that remain high over time can damage your eyes, kidneys, nerves, and blood vessels.

Blood glucose tests are done to:

• Check for diabetes.
• Monitor treatment of diabetes.
• Check for diabetes that occurs during pregnancy (gestational diabetes).
• Determine if an abnormally low blood sugar level (hypoglycemia) is present. A test to measure blood levels of insulin and a protein called C-peptide may be done along with a blood glucose test to determine the cause of hypoglycemia. For more information, see the medical test C-Peptide.

Amazingly, healthy people without diabetes usually have a tightly controlled level of blood sugar between 6 - 8 mmol/L, no matter how much they eat, or even in elevated stress levels.

This is because the blood glucose is controlled by a complex interaction of multiple chemicals and hormones in the body, including the hormone insulin made in the beta cells of the pancreas.

Mechanism of insulin release in normal pancreatic beta cells. Insulin production is more or less constant within the beta cells, irrespective of blood glucose levels. It is stored within vacuoles pending release, via exocytosis, which is primarily triggered by food, chiefly food containing absorbable glucose. The chief trigger is a rise in blood glucose levels after eating.