Glucose in your bloodstream is your body’s main energy source for basic cellular function. When you eat foods that contain carbohydrates, your body breaks them down and extracts their glucose content for immediate and future use. (See References 1) Regulation of glucose in your bloodstream and elsewhere in your body requires the coordinated action of your pancreas and your liver. (See References 2 and 3)
Insulin
When glucose content in your blood rises, specialized cells in your pancreas called beta cells release a hormone called insulin into your bloodstream, according to EndocrineWeb. Once in your blood, insulin sends signals to various types of cells that tell them to allow blood glucose into their interiors. Cell types that respond to insulin’s signals include fat and muscle cells and red blood cells. In addition to providing cells with energy, the ultimate effect of insulin’s activities is a lowering of your blood glucose and maintenance of proper glucose levels. As your glucose levels fall, insulin secretion slows to a trickle. (See References 2)
Glycogen and Glucagon
Excess glucose in your bloodstream is stored in your liver and muscles as a substance called glycogen, according to Discovery Health. (See References 3) When your blood glucose levels drop between meals or during exercise, your pancreas secretes a hormone called glucagon. As glucagon levels rise, they encourage your liver to convert glycogen back to glucose for use in your bloodstream. Your liver and muscles also make glucose out of amino acids and other cellular materials. When glucose levels in your blood rise, your pancreas stops producing glucagon. As with insulin, the overall effect of glucagon secretion is maintenance of proper glucose levels in your bloodstream. (See References 2 and 3)
Normal Glucose
Normal glucose levels in your bloodstream range between 70 and 110 milligrams per deciliter of blood, EndocrineWeb reports. When you eat, your glucose levels may safely reach as high as 180 mg/dL in a period of two or three hours. If your blood glucose falls below 70 mg/dL, you may have a condition called hypoglycemia, or low blood sugar. If you have not eaten and your blood glucose rises above 110 mg/dL, you may have a condition called hyperglycemia, or high blood sugar. If you have eaten and your glucose rises above 180 mg/dL, you also may have hyperglycemia. If your blood glucose rises above 200 mg/dL during specialized testing, you have a condition called diabetes. (See References 2)
Glucose Alterations
In addition to diabetes, the National Library of Medicine’s Medline Plus lists potential causes of high blood sugar that include abnormally high thyroid function, pancreatitis, pancreatic cancer and Cushing's syndrome. You may develop low blood sugar if you have abnormally low function in your thyroid or pituitary glands. Additional causes include inadequate food intake and overuse of insulin or other glucose-control medications. (See References 1)
Temporary Changes
You can also experience temporary glucose elevations from sources of stress such as heart attacks, surgery, strokes and physical trauma, Medline Plus notes. Drugs known to raise glucose readings include diuretics, corticosteroids, lithium and tricyclic antidepressants. Substances known to lower glucose readings include anabolic steroids, acetaminophen, monoamine oxidase inhibitors, gemfibrozil and alcohol. (See References 1)
