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How can I find out if my glucose monitor kit is accurate?

Stacy Wiegman, PharmD
Pharmacy Specialist

Most glucose monitor kits come with a test solution. You will need to squeeze a drop of this solution on to a test strip and insert it into your monitor. You should test the solution as you would test your blood. After the monitor has determined the amount of glucose in the solution, you should compare it to the amount printed on the solution bottle. If the two numbers are the same, you know your glucose monitor kit is functioning properly.

To ensure your results are accurate, you should use the test solution each time you open a new box of test strips. You should also use the solution periodically as you do your regular blood testing. Always test your monitor if you receive a blood sugar reading that is odd.

To find out if your glucose monitor kit is accurate there are a couple of points to keep in mind:

  • Check that the strips purchased are not expired.
  • Make sure the strips match the meter. You will see a number on the side of the strip bottle. The same number should show up on your meter's screen once you insert the strip into the machine. This is known as coding your meter.
  • Storage of strips is also an important step for precise blood sugar readings. Improperly stored strips can diminish the meter's ability to properly read your blood sample. Be sure to store your strips away from extreme heat, cold, humidity and moisture. Keep your strips at room temperature in the original packaging they arrived in.
  • Use a control solution. Control solutions are also meter specific and expire, so be sure to check that the solution is still viable and for your meter! The control solution will have an acceptable range your meter should read. If the number on your meter reads outside of that range, contact your primary care doctor or endocrinologist.
William Lee Dubois
Endocrinologist

So the first thing you need to know about meter accuracy, is that they are not accurate at all, even when they are working perfectly. Currently, here in the States, a meter only needs to be within 20 percent of a lab value for FDA approval. To put that into some kind of perspective, consider the following:

  • If your blood sugar is 100 mg/dL, your meter could read anywhere between 80 and 120.
  • If your blood sugar is 200 mg/dL, your meter could read anywhere between 160 and 240.
  • If your blood sugar is 300 mg/dL, your meter could read anywhere between 240 and 360.
  • If your blood sugar is 400 mg/dL, your meter could read anywhere between 320 and 480, a one hundred and sixty point spread.

Now, none of this was meant to depress you. Test strips are getting better and better, especially the ones from the big names in the business such as OneTouch and FreeStyle. WaveSense strips are also frighteningly good too. But what I want you to understand is that if you test a single drop of blood with two strips in a row, you will not get the same answer each time—and that doesn’t mean something is wrong with your meter.

Most meters come with a vial of test solution, which is fake blood with a set amount of sugar in it. You can use the test solution to make sure your meter is working within the normal operating range. You simply take a test just like you would test your blood sugar, but instead of lancing you finger and testing your blood, you put a drop of test solution on the tip of your finger and test it.

Each vial of test strips will have a range of expected results printed on it. So long as the test you took falls within those numbers, the meter is working normally.

One important note, however, is that about half the meters available need to be coded to match each batch of test strips. This may be done with a chip that comes with the strips and needs to be plugged into the side of the meter, or by using the key pad on the meter to enter a one- or two-digit number that is printed on the vial of strips.

Many newer meters are “self coding,” but if you have a meter that requires coding and it is not properly coded, it can be off by as much as 80 percent.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.