HEALTH FEATURE ARCHIVE
Diabetes 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 health care provider. Self-monitoring of blood glucose (SMBG) is recommended for all people with diabetes, but especially for those who take insulin.
Learning to Use Your Glucose Meter
Not 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
The 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.
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 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 meter should have a website. Check this website regularly to see if it lists any issues with the function of your meter.
Important Features Of Glucose Meters
There 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.
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."
Cleaning: Some 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 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 Performance
The 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: 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.
Other Substances: 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.
Altitude, Temperature and Humidity: Altitude, room temperature, and humidity can cause unpredictable effects on glucose results. Check the meter and test strip package insert for information on these issues. Store and handle the meter and test strips according to the instructions.
Third-Party Test Strips: Third-party or "generic glucose reagent strips" are test strips developed as a less expensive option than the strips that the manufacturer intended the meter to be used with. They are typically developed by copying the original strips. Although these strips may work on the meter listed on the package, they could look like strips used for other meters. Be sure the test strip you use is compatible with your glucose meter.
Sometimes manufacturers change their meters and their test strips. These changes are not always communicated to the third-party strip manufacturers. This can make third-party strips incompatible with your meter without your knowledge. Differences can involve the amount, type or concentration of the chemicals (called "reagents") on the test strip, or the actual size and shape of the strip itself. Meters are sensitive to these features of test strips and may not work well or consistently if they are not correct for a meter. If you are unsure whether or not a certain test strip will work with you meter, contact the manufacturer of your glucose meter.
Making Sure Your Meter Works Properly
You should perform quality-control checks to make sure that your home glucose testing is accurate and reliable. Several things can reduce the accuracy of your meter reading even if it appears to still work. For instance, the meter may have been dropped or its electrical components may have worn out. Humidity or heat may damage test strips. It is even possible that your testing technique may have changed slightly. Quality control checks should be done on a regular basis according to the meter manufacturer's instructions. There are two kinds of quality control checks:
Check Using "Test Quality Control Solutions" or "Electronic Controls": Test quality control solutions and electronic controls are both used to check the operation of your meter. Test quality control solutions check the accuracy of the meter and test strip. They may also give an indication of how well you use your system. Electronic controls only check that the meter is working properly.
Test quality control solutions have known glucose values. Essentially, when you run a quality control test, you substitute the test solution for blood. The difference is that you know what the result should be.
To test your meter with a quality control solution, follow the instructions that accompany the solution. These will guide you to place a certain amount of solution on your test strip and run it through your meter. The meter will give you a reading for the amount of glucose in the sample. Compare this number to the number listed on the test quality control solution. If the results of your test match the values given in the quality control solution labeling, you can be assured the entire system (meter and test strip) is working properly. If results are not correct, the system may not be accurate--contact the manufacturer for advice.
Manufacturers sometimes include quality control solution with their meter. However, most often you must order it separately from a manufacturer or pharmacy.
Some glucose meters also use electronic controls to make sure the meter is working properly. With this method, you place a cartridge or a special "control" test strip in the meter and a signal will appear to indicate if the meter is working.
Take Your Meter with You to The Health Care Provider's Office: This way you can test your glucose while your health care provider watches your technique to make sure you are using the meter correctly. Your healthcare provider will also take a sample of blood and evaluate it using a routine laboratory method. If values obtained on the glucose meter match the laboratory method, you and your healthcare provider will see that your meter is working well and that you are using good technique. If results do not match the laboratory method results, then results you get from your meter may be inaccurate and you should discuss the issue with your healthcare provider and contact the manufacturer if necessary.
How FDA Regulates Glucose Meters
FDA reviews all glucose meters and test strips before they can be marketed to the public. This FDA "premarket" review process requires the manufacturer of the meter to show that the meter system provides acceptable accuracy and consistency of glucose measurement at high, medium and low levels of glucose as compared to glucose meters already being sold. The quality of software is an increasingly important feature of glucose meters since it controls the testing and data storage and controls the displays that the user sees and uses when testing.
FDA also asks for data showing how well the meter has performed during actual use (a type of human factors study). These studies ensure that users understand the labeling, achieve good results, and avoid experiencing problems that could affect their health.
FDA quality system regulations require that manufacturers who make glucose meters follow the same quality standards every time. In this way, users can be assured that new meters and strips perform as well as older models.
FDA's responsibility for medical devices does not end when the devices enters the market. To monitor the quality of products, FDA routinely inspects manufacturing facilities. It also receives information from the manufacturers, health providers and the general public through the MedWatch system.
Reporting Problems with Glucose Meters to FDA
FDA learns about problems with medical products through the MedWatch program.
Consumers can report problems with medical devices, including glucose meters,
For general information about the MedWatch program and instructions for reporting problems with medical devices, use the following link:
MedWatch: The FDA Safety Information and Adverse Event Reporting Program
For more, please visit Diabetes Center.
Portions of the above information has been provided with the kind permission of the Food and Drug Administration.