Glucose Level Information

Glucose is a sugar that is made when carbohydrates, sugar and starches are digested. It is the body's prime source of energy. Insulin and glucose work together to give the body energy. Doctors often test patient's glucose levels because if the levels are too high or too low, illness can result.

Testing

• If your blood glucose levels are being tested, you will be asked to give a blood sample. There are various types of tests to measure your blood glucose level. You will be asked to fast at least eight hours for a fasting blood sugar test. If you are having a two-hour postprandial blood sugar test, your glucose levels will be measured exactly two hours after you eat a meal. In a random blood sugar test, your blood glucose level will be measured without any restriction on when you last ate. If this type of test is conducted, many tests are usually done throughout the day. In an oral glucose tolerance tests, your blood glucose levels will be measured after you drink a liquid containing glucose.

Purpose

• Blood glucose levels are measured for various purposes. Most commonly, the blood glucose tests are done to check whether you have diabetes or as part of monitoring treatment of diabetes. The test may also be done to determine if you have hypoglycemia, a condition in which blood glucose levels are extremely low. The tests are dependent upon when you last ate because blood glucose levels rise slightly after a meal. This rise in levels causes the pancreas to send insulin to keep the glucose levels from getting too high.

Normal

• Normal blood glucose levels depend upon which type of test was conducted. If you had a fasting test, your levels should be 70 to 99 mg/dL (milligrams per deciliter). If the test was a postprandial test, your levels should be 70 to 145 mg/dL. In a random test, the levels should be 70 to 125 mg/dL. For a pregnant woman, the normal range in an oral glucose test is less than 140 mg/dL. Some doctors may have a lower standard and consider the patient to be at risk of gestational diabetes if her glucose levels are above 130 mg/dL.

High

• If the glucose levels are high, it may indicate that you have diabetes or are at risk of developing the illness. The American Diabetes Association's standards state that diabetes can be diagnosed if you blood glucose levels tests at certain levels for two days in a row. With a fasting test, the level is 126 mg/dL or higher. If the fasting level is 100 mg/dL to 125 mg/dL, you may have pre-diabetes. Heart attack, stroke, Cushing's syndrome, steroid usage or excess growth hormones can also cause high glucose levels.

Low

• If your fasting blood glucose level is less than 40 mg/dL and you are female, or less than 50 mg/dL and you are male, the blood glucose level is considered low. If the range is accompanied by symptoms of hypoglycemia, it may indicate insulinoma, which causes your body to produce too much insulin. Other conditions that can cause low blood glucose levels are Addison's disease, hypothyroidism, pituitary gland tumors, liver disease, kidney failure or malnutrition.