Glucose Meters (Glucose Monitors)
How to Measure Blood Sugar
A glucose meter or monitor is a machine that measures how much glucose (sugar) is in the blood. Typically, a specially coated strip containing a sample of blood is inserted in the machine, which then measures the level of glucose in the blood sample and shows the result on a digital display. Some glucose meters/monitors have a memory component that can store results from multiple tests. Monitor Blood Glucose and Maintain Glycemic Diet ControlThis glucose-measuring equipment is mainly used by diabetics to monitor glucose levels which need to be kept in balance in order to reduce the risk of hypoglycemia (low blood sugar) and hyperglycemia (high blood sugar). But a glucose meter/monitor home health test kit can help you maintain good glycemic control through diet, exercise, blood monitoring and medication.Helpful Tips About Your Glucose Meter/MonitorDiabetes care should be designed for each individual patient. Some patients may need to test (monitor) blood glucose more often than others do. How often you use your glucose meter should be based on the recommendation of your diabetes educator or doctor. Self-monitoring of blood glucose (SMBG) is recommended for all people with diabetes, but especially for those who take insulin (type 1 diabetics). Learning to Use Your Glucose Meter/MonitorNot all glucose meters work the same way. Since you need to know how to use your glucose meter and interpret its results, you should get training from a diabetes educator. The educator should watch you test your glucose to make sure you can use your meter correctly. This training is better if it is part of an overall diabetes education program.Instructions for Using Glucose Meters/MonitorsThe following are the general instructions for using a glucose meter:
- Wash hands with soap and warm water and dry completely or clean the area with alcohol and dry completely.
- Prick the fingertip with a lancet.
Hold the hand down and hold the finger until a small drop of blood appears; catch the blood with the test strip.
- Follow the instructions for inserting the test strip and using the SMBG meter.
Record the test result.
- The Food and Drug Administration (FDA) requires that glucose meters and the strips used with them have instructions for use. You should read carefully the instructions for both the meter and its test strips. Meter instructions are found in the user manual. Keep this manual to help you solve any problems that may arise. Many meters use “error codes” when there is a problem with the meter, the test strip, or the blood sample on the strip. You will need the manual to interpret these error codes and fix the problem.
You can get information about your glucose meter and test strips from several different sources. Your user manual should include a toll free number in case you have questions or problems. If you have a problem and can’t get a response from this number, contact your healthcare provider or a local emergency room for advice. Also, the manufacturer of your glucose meter should have a website.Important Features Of Glucose Meters/MonitorsThere are several features of glucose meters that you need to understand so you can use your meter and understand its results. These features are often different for different meters. You should understand the features of your own meter.
Glucose Meter Measurement Range
Most glucose meters are able to read glucose levels over a broad range of values from as low as 0 to as high as 600 mg/dL. Since the range is different among meters, interpret very high or low values carefully. Glucose readings are not linear over their entire range. If you get an extremely high or low reading from your meter, you should first confirm it with another reading. You should also consider checking your meter’s calibration.
Whole Blood Glucose vs. Plasma Glucose
Glucose levels in plasma (one of the components of blood) are generally 10-15% higher than glucose measurements in whole blood (and even more after eating). This is important because home blood glucose meters measure the glucose in whole blood while most lab tests measure the glucose in plasma. There are many meters on the market now that give results as “plasma equivalent”. This allows patients to easily compare their glucose measurements in a lab test and at home. Remember, this is just the way that the measurement is presented to you. All portable blood glucose meters measure the amount of glucose in whole blood. The meters that give “plasma equivalent” readings have a built in algorithm that translates the whole blood measurement to make it seem like the result that would be obtained on a plasma sample. It is important for you and your healthcare provider to know whether your meter gives its results as “whole blood equivalent” or “plasma equivalent.”
Glucose Meter Cleaning
Some glucose meters need regular cleaning to be accurate. Clean your meter with soap and water, using only a dampened soft cloth to avoid damage to sensitive parts. Do not use alcohol (unless recommended in the instructions), cleansers with ammonia, glass cleaners, or abrasive cleaners. Some glucose meters do not require regular cleaning but contain electronic alerts indicating when you should clean them. Other meters can be cleaned only by the manufacturer.
Display Of High And Low Glucose Values
Part of learning how to operate a meter is understanding what the meter results mean. Be sure you know how high and low glucose concentrations are displayed on your meter.Factors That Affect Glucose Meter PerformanceThe accuracy of your test results depends partly on the quality of your meter and test strips and your training. Other factors can also make a difference in the accuracy of your results.
Hematocrit is the amount of red blood cells in the blood. Patients with higher hematocrit values will usually test lower for blood glucose than patients with normal hematocrit. Patients with lower hematocrit values will test higher. If you know that you have abnormal hematocrit values you should discuss its possible effect on glucose testing (and HbA1C testing) with your health care provider. Anemia and Sickle Cell Anemia are two conditions that affect hematocrit values.
Many other substances may interfere with your testing process. These include uric acid (a natural substance in the body that can be more concentrated in some people with diabetes), glutathione (an “anti-oxidant” also called “GSH”), and ascorbic acid (vitamin C). You should check the package insert for each meter to find what substances might affect its testing accuracy, and discuss your concerns with your health care provider.