Glucose is a sugar, or simple carbohydrate. It is one of the main chemicals typically found in the blood. The digestion of a meal, or breakdown of stored glucose in the liver and muscles, increases glucose levels in the blood. Insulin signals cells to take up glucose, which is then used to make ATP, the energy-carrying molecule of the cell. Healthy fasting glucose levels indicate normal regulation of blood glucose. Low or, much more commonly, high levels indicate the presence of a health condition and should be discussed with a licensed health care professional.
Normal Glucose Levels
Normal glucose levels range from about 70 mg/dL to 100 mg/dL. Levels below this are considered low blood sugar, or hypoglycemia. Levels over 100 mg/dL to 125 mg/dL are considered to be impaired fasting glucose, or pre-diabetes. Levels higher than 125 mg/dL are evidence for diabetes.
Assays
An assay is a test. Assays for blood glucose include blood glucose tests, oral glucose tolerance test and hemoglobin A1c. All of these give information about how the body is processing glucose. Fasting and random glucose tests determine the concentration of glucose in the blood in a hungry state or at a random time, respectively. Oral glucose tolerance tests involve giving an oral load of sugar, then measuring the glucose level. Hemoglobin A1c measures the amount of protein in the blood bound by sugar molecules.
Health Maintenance
Healthy fasting glucose levels are promoted by a healthy lifestyle, such as proper diet and exercise. A diet of fruits and vegetables, whole grains, low sodium, low fat and cholesterol, without sugary snack foods and beverages and which is calorie restricted should help keep glucose levels normal. People who are overweight should eat fewer calories than they expend in a day, with the guidance of a physician or registered dietitian, to lose weight. Exercise helps regulate blood glucose and is beneficial to the heart, but should be undertaken after consulting a physician.
Elevated Fasting Glucose Treatment
The primary treatment for mildly elevated fasting blood glucose is appropriate diet and exercise. Medications also are available that lower blood glucose. For example, metformin decreases the release of glucose from the liver. Insulin can be administered under the skin to help signal the cells to take up glucose.
Hypoglycemia
Excessive administration of insulin and several other medications can induce low blood sugar, which requires immediate treatment with food or or intravenous, or IV, administration of simple sugars such as IV dextrose. Low blood sugar deprives the cells of energy and causes symptoms such as fatigue, mental status changes, and even coma and death. Other causes include inadequate food intake and, rarely, tumors in the pancreas called insulinomas, which produce insulin.
References
- "Physiology (fourth edition)"; Linda Costanzo; 2008
- "Harrison's Principles of Internal Medicine (17th edition)"; Anthony Fauci et al; 2008
