Glucose is a simple sugar known as a monosaccharide that is utilized as the body's primary source of energy. Glucose is produced from carbohydrates, proteins and fats, and is transferred through the bloodstream to the body's cells. The cells then rely on insulin to break down the glucose, and use it in a variety of cell processes.
Testing Glucose Levels
A glucose test can be administered for a number of reasons. It is used to help diagnose hyperglycemia and hypoglycemia, and is often performed on women during their twenty-fourth to twenty-eighth week or pregnancy to detect gestational diabetes. Urine glucose may be checked as part of urine analysis during diagnosis of a urinary tract infection. Diabetics usually perform a few glucose tests each day to track their glucose levels. A glucose test is often ordered for someone suffering from fainting spells or experiencing prolonged abnormal behavior, and seizure victims are also often issued glucose tests.
While there are a few ways to test glucose levels, it is often measured with a blood sample from the patient which is analyzed to determine the amount of glucose present in the bloodstream. This can be done at random or after a "fasting" period for the patient. Usually the fasting requires the patient to abstain from eating or drinking eight to 10 hours prior to the test.
High Glucose
While results can vary across different laboratories, a typical normal amount for a fasting patient is between 70 to 100 mg of glucose per deciliter of blood. Higher than normal glucose levels are called hyperglycemia and are usually indicative of diabetes. Levels between 100 to 125 mg/dL indicates impaired fasting glucose, also called prediabetes. Patients in this level are considered at risk of type 2 diabetes, while those with levels higher than 125 mg/dL are usually diagnosed with diabetes.
High glucose levels can also indicate glucagonoma, hyperthyroidism, pancreatic cancer or pancreatitis. In rare circumstances, high glucose levels may indicate pheochromocytoma, acromegaly or cushing syndrome. Abnormally high levels of glucose often produce symptoms such as blurry vision or dizziness, an increase in thirst and fatigue, increased urination and slower healing from infections.
Low Glucose
Glucose levels below 70 mg/dL are lower than normal and indicate hypoglycemia, which in turn can signal the presence of disorders such as hypopituitarism, hypothyroidism or, in rare circumstances, insulinoma. Low levels could also be nothing more than the result of too little food and nutrition, or too much insulin or other medication for diabetics. Low glucose levels are often marked by increased sweating, a bigger appetite, body shakes or trembling, and even psychological effects such as increased anxiety and confusion.
