Blood glucose tests are a common, but accurate, method of evaluating your body's ability to process carbohydrates into glucose. Glucose is an important source of fuel for your brain, muscles and other organs. Blood glucose starts out as carbohydrates in the diet. After the carbohydrates are broken down into glucose by the small intestines, they enter the bloodstream where they are delivered to the cells of the body. Even healthy, disease-free individuals experience transient changes in their glucose levels.
Carbohydrate Challenges in the Diet
Fasting blood glucose levels in healthy individuals typically range from 70 to 100 mg/dl. After a carbohydrate-rich meal, glucose levels can exceed 200 mg/dl or more but should return to normal within one hour after eating. This is the reason why your doctor will instruct you to fast for 10 to 12 hours before having your blood drawn for a routine glucose test.
Diabetes
Diabetes is a serious metabolic disease that results in high levels of blood glucose. Depending on the type of diabetes (Type 1 or Type 2), high glucose levels can be caused by a shortage of insulin--a hormone produced by the pancreas. It can also be caused by the tissue's insensitivity to insulin. If the tissues can't use insulin, the cells can literally starve in the presence of high glucose levels. If your doctor suspects that your fasting blood glucose levels are high, he may order additional tests to rule out pre-diabetes.
Other Conditions
In addition to diabetes, there are a number of other conditions that can raise glucose levels and cause abnormal glucose test results. Heart attacks and strokes can raise blood glucose levels as a result of increased adrenaline. Cushing's syndrome and corticosteroids can also increase blood glucose levels. Cushing's syndrome can be caused by long-term use of corticosteroids, tumors on the pituitary gland or adrenal gland and some types of cancer. Corticosteroids are prescribed as prednisone, dexamethasone and hydrocortisone, and in addition to causing high blood sugar, can cause weight gain, stomach ulcers, hypertension and cataracts.
