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 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.
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.