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U.S. Department of Health and Human Services

Medical Devices

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Useful Tips to Increase Accuracy and Reduce Errors in Test Results from Glucose Meters

Have you ever wondered why you got a bad glucose meter test result when there is nothing obvious wrong with your meter, your test strips are new, and you’ve been running glucose tests for years? The simple answer is that glucose meters are not perfect, and neither are the people who use them! This chart lists some tips to help you get the most accurate results from your glucose meter.

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  • follow the user instructions about sample size. Repeat the test if you have any doubt that enough blood was added.
If there is insufficient blood on the test strip, the meter may not be able to read the glucose level accurately. Although many meters are designed to alert you when the sample size is too small, some meters detect only large errors. There have been cases where meters have displayed glucose levels that were less than half the actual levels without displaying error messages.
  • insert the test strip completely into the meter guides.
When a test strip is not fully inserted into the meter, the meter cannot read the entire strip area. Many meters are designed to detect strip placement errors and will not provide a result. But, just as described above, many meters detect only large problems. There have been cases where meters have displayed glucose levels that were significantly higher or lower than the actual levels when there was only a small error in strip placement.
  • keep the meter clean.
Even small amounts of blood, grease, or dirt on a meter’s lens can alter the reading.
  • check the test strip package to make sure the strips are compatible with your meter.
Test strips are not always interchangeable, and meters cannot always detect incompatible strips. Test strips that look alike may have different chemical coatings. Small variations in strip dimensions can also affect results.
  • check the expiration date on the test strips.
As a test strip ages, its chemical coating breaks down. If the strip is used after this time, it may give inaccurate results.
  • enter the correct calibration code from the outside of the strip bottle each time you run a test (if applicable).
Results can vary significantly between manufactured lots of reagent strips; the calibration codes help the meter compensate for these variations.
  • run quality control as directed.
Running quality control is typically the only way to know when test strips have gone bad. Test strips do not always last until the expiration date on the bottle. This may be because the manufacturer has over-estimated the dating or because the cap was not replaced promptly after use.
  • check the results from your meter against laboratory results as often as possible.
Over time, test systems can drift apart. Since results from either test system maybe used to treat your patients, it is important for the systems to remain synchronized.
  • question results that are not consistent with physical symptoms. If a test result seems wrong, have a blood sample tested by the main laboratory.
There may be many reasons why a test result is incorrect. In addition to the items above, some physiological conditions such as dehydration, hyperosmolarity, high hematocrit, or shock may significantly affect test results.