Blood sugar is to your body what gas is to your car --- fuel. Your body uses several mechanisms to regulate your blood sugar level, ensuring an adequate circulating supply and storing excess for future use. When all of the control systems function properly, nondiabetics typically have blood sugar levels within a narrow normal range. Certain medical conditions, however, may cause blood sugar abnormalities among nondiabetics.
Normal Range
The normal range for your blood sugar, or glucose, depends on the timing of your last meal. Your fasting blood glucose --- the level when you have not had anything to eat or drink for at least eight hours --- is normally 70 to 99 mg/dL. Blood sugar levels in nondiabetics normally increases to as high as 139 mg/dL after meals, as sugars from food are absorbed into your bloodstream. Peak blood sugar levels characteristically occur approximately two hours after you've eaten and gradually decrease as the sugar load is either used or stored.
Hormonal Control
Your diet supplies most of the glucose in your body. Your liver also manufactures glucose and serves as a storage depot for this important sugar. Under normal circumstances, two hormones secreted by the pancreas regulate your blood glucose level by directing dietary and liver glucose metabolism.
Insulin
Insulin has blood-sugar-lowering effects. It is normally secreted when your blood glucose level reaches 90 mg/dL or higher. As you might expect, insulin secretion is greatest when you eat. Insulin lowers your blood sugar level by enabling passage of glucose into your cells, shutting down liver production, and stimulating glucose storage. These effects prevent your blood sugar level from increasing to an abnormal level. Insulin release by your pancreas normally slows dramatically when your blood glucose level decreases to approximately 72 mg/dL.
Glucagon
Glucagon has the opposite effect of insulin, functioning to increase your blood sugar level. A decrease in your blood sugar level to approximately 72 mg/dL stimulates the release of glucagon. Glucagon promotes the release of stored sugar and liver glucose production. Your pancreas secretes glucagon primarily between meals to maintain your glucose level and prevent a low blood sugar, or hypoglycemia.
Blood Sugar Abnormalities in Nondiabetics
Hormones other than insulin and glucagon can affect your blood sugar level. Growth hormone from your pituitary gland and cortisol and epinephrine from your adrenal glands promote increased blood sugar levels. Tumors and other conditions that cause overproduction of these hormones often lead to an abnormal elevation in blood sugar. Major trauma, severe infections and other serious illnesses can also cause blood sugar abnormalities. Medications, especially steroids, may cause a temporary increase in your blood sugar level.
References
- National Institute of Diabetes and Digestive and Kidney Diseases: Hypoglycemia
- MedBio.info; Insulin and Glucagon; Robert S. Horn, Ph.D.; December 2009
- "Endocrine Practice"; American Association of Clinical Endocrinologists Medical Guidelines for Clinical Practice for the Management of Diabetes Mellitus; Helena W. Rodbard, M.D., et al.; May--June 2007
- "Diabetes Care"; Diagnosis and Classification of Diabetes Mellitus; American Diabetes Association; December 2010
- "The Endocrine Response to Acute Illness"; Richard C. Jenkins, B.Med.Sci., Richard J. M. Ross, M.D.; 1999
