According to the American Diabetes Association, over 23 million Americans have the disease. Diabetes is a serious metabolic disorder that affects the way the body metabolizes glucose in the blood. Left unmanaged, diabetes can result in heart disease, kidney failure, nerve damage and blindness. When diabetics are first diagnosed, their doctors tell them how important it is to manage their blood glucose levels. Diabetics learn how to test their blood glucose using a variety of methods and compare them against clinical laboratory results. This is especially important when making changes in diet, exercise routines or medications.
Testing of Blood Sugar
The first time a patient suspects she is pre-diabetic, she will exhibit common symptoms of diabetes that include unquenchable thirst, rapid weight loss, urination, nausea and fatigue. If your doctor suspects that you have diabetes, he'll ask you to return to his office after a 12-hour fast for a blood glucose test. A nurse or a trained laboratory technician draws a small sample of your blood and analyzes it for blood glucose concentration. The normal range of blood glucose after a 12-hour fast is 70 to 110 mg/d. If your test comes back with results that are above normal, the doctor may ask you to either repeat the test or take an oral glucose tolerance test.
It's important that you take the test after fasting - even small amounts of carbohydrates can affect the test results. It's also a good idea to not exercise and drink plenty of water before the test. Exercising can cause temporary drops in glucose levels and dehydration can abnormally high results.
Oral Glucose Tolerance Tests
An oral glucose tolerance test (OGTT) is the next level of clinical tests for diabetes. It is frequently used with Type II diabetics and pregnant women who have gestational diabetes. After fasting overnight, you're asked to drink a highly concentrated glucose drink containing between 75 and 100g of glucose. Blood is drawn every 30 to 60 minutes for up to three hours to determine how fast your body metabolizes the glucose. The normal response is blood glucose below 140 mg/dl after two hours. If your values fall between 140 to 199 mg/dl, you have impaired glucose tolerance. Any values higher than 199 mg/dl means you are probably diabetic.
Hemoblobin A1c
Another clinical test that is commonly used to diagnose diabetes is hemoglobin A1c. Hemoglobin is the oxygen-carrying protein inside red blood cells. It is responsible for transporting oxygen to the body's tissues. Hemoglobin can also grab onto blood glucose--especially when it is in high concentrations. Diabetics are frequently tested for hemoglobin A1c (HbA1c) because it can produce more accurate information about how well you're managing your disease. The HbA1c values represent average blood glucose levels over the lifespan of your red blood cells--about 120 days. It is often used to monitor long-term changes in diet, exercise and medications. The normal value for HbA1c is 4 to 6 percent. Any value higher than 6 percent could diagnose unmanaged diabetes.
Traditional Home Monitoring
Once your doctor has established the proper approach to your diabetes, he'll expect you to monitor your own blood glucose levels between visits. There are dozens of types of monitors that cost between $59 and $100 as of August 2009. While they all measure blood glucose levels, some are more accurate than others. Some models include expanded memory that will remember glucose readings for a year, average them and allow you to upload the results to your home computer. Most home blood sugar monitors require you to prick the end of your finger with a lancet (a sharp needle). After putting a drop of blood on a test strip and inserting it into the meter, the meter will display your blood sugar level. There are also models that allow you to test sites other than your fingertips, such as your forearm, side of your thumb or thigh. This can be a good feature when you have to monitor your blood glucose many times a day.
Newer Testing Methods
There are also a number of other newer tools for testing blood glucose. These include lasers that draw blood, MiniMed continuous glucose montoring systems and the Glucowatch. Lasers send a beam of light through your skin to analyze glucose concentrations. MiniMed systems use a mini-catheter below the surface of the skin to measure blood samples. The Glucowatch is worn like a wristwatch, and measures blood glucose levels three times an hour by sending tiny electrical currents through the skin.
