Blood Glucose Accuracy
Home glucose testing monitors aren’t as accurate as lab tests. They have a significant margin for error. We’ve also found that most suppliers try to keep this a secret. It’s not good for business to contradict a positively held myth about one’s own product. Because of this practice, even people who have been diabetics for decades have never realized that their testing meters can register differences of up to 20 percent off the same blood sample.
Accuracy will always be a relative. Let us use the example of a dart on a dartboard. A bull’s-eye is about an inch in diameter. If you hit the bull’s-eye, would you consider yourself to have made an accurate throw? Some would say so, but there are others who would inspect closer to determine where in the actual bull’s-eye you hit. Did you it in the center, or on the edge? Would hitting just outside the edge of a bull’s-eye be described as accurate, or inaccurate? It is relative to the observer.
However, it is important to remember that this article is not our attempt to justify the relative accuracy of home testing meters. Instead, this page is meant to state a verifiable and inconvenient fact. The international standard for home testing meters is somewhere around 20 percent accuracy, 95 percent of the time (with the other 5% allowing for wild variations). While most meters do have more accurate results than that standard, they are not 100 percent accurate.
So the question then is why aren’t these meters accurate? The answer is simple. Don’t let the perfect be the enemy of the good. These tests are accurate enough for what we use them for
The simple answer is, there are many variables. Do you have a microscopic foreign substance on your meter, strips, or fingers? Everyone does, no matter how well you clean. The question is, how much will it affect your test. Have the strips passed their ideal shelf life? Has the bottle been left open and exposed to humidity? Was there a minute manufacturing defect in your meter or strips? Was your blood pressure high when you tested? Were you dehydrated? Technology has not progressed to a level that will allow these meters to be 100 percent accurate. If that was the case, we wouldn’t need lab tests./p>
In a lab test, just being in a lab or clinic takes away a lot of those environmental variables. A lab test also draws a larger sample size. One drop of blood might have slightly more or less blood glucose than another. So why don’t home glucose testing strips ask for a larger blood sample? A larger sample isn’t practical with home glucose testing.
There is always the possibility that your meter or strips are giving you inaccurate results. However, relying on how you feel is not an accurate measurement of blood glucose. After years of educating patients on testing meters we have only found two ways that verify meter results.
1. Preform a control solution test. Directions for this test can be found online or in your meter manual.
2. Compare your results to a lab test. Remember, if you wait too long before or after drawing blood for the lab test, the test on your home meter will not be relevantly comparable. Ideally you would want to test your blood with your home glucose meter at the same time the doctor’s office is drawing blood. If you are within 20 percent of the lab test, that meter should be considered correctly calibrated, and relatively accurate.
*The author of this blog is not a medical professional and this article does not contain professional medical advice. This blog is not intended to substitute for medical advice, treatment, or diagnosis. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of the contents of this article. If you think you may have a medical emergency, call 911 immediately.