Where might I find some stats concerning the accuracy of certain meters? From what my doctors tells me many are not very accurate. Is this true? Today my meter and the doctor's professional one had 30 points variation.
The American Diabetes Association held a conference in 1993 on blood glucose self management. There one of the concerns was meter accuracy. One cannot expect a small meter to have the accuracy of a machine that costs tens of thousands of dollars.
That said, meters must meet FDA standards before release to the market. I believe one way to get a sense of the potential accuracy of a meter is to look at the control solutions or the check strips provided by the manufacturers. The ranges that are acceptable give you a sense of the potential accuracy of the meter. Many people are surprised at the range of the control solutions or the range of the check strips. That is as good as it gets now. The meters are just that good. While writing I looked at a strip bottle. It said the normal glucose control range is from 93-132. Other lots of strips will have a different range for the same control solution. In practice, I see some technique dependence. That is less of a problem that in earlier models of glucose meters, but there is still some technique to doing the test. Most people get values at a point in the range. If you tend to get lower controls, that is closer to the lower acceptable range and do it repeatedly, I expect your technique has determined that fact.
Dr. William Clarke and his colleagues at the University of Virginia proposed an error grid a few years ago. This grid plots the glucose obtained from the meter against the glucose obtained in a lab. There is a range of glucoses that are acceptable. Dr. Clarke would say that if you get a value from the meter that is okay, say 80, and the true value is 30, then you can have a problem. He plots these values in what he calls the D zone or danger zone. That really is the issue. For most values, being close to the "truth" is okay and doesn't change the clinical decision.
Finally the standards for glucose meters is changing. Historically self-monitoring of blood glucose used capillary glucose as the standard. Labs generally use plasma glucose as the standard, which is about 10-15% higher than capillary. Because so many patients were comparing their results to the doctor, newer meters are now all set at plasma glucose. Now when you compare one meter to the other, you may truly be comparing apples and oranges. Check to see which standard your meter is using. When you change meters your doctor may even wish to change your target range.
I tell patients that they must practice, use the check strips, and control solutions as well as bring the meter to the clinic visit and let my diabetes educator make sure the meter is working and the operator is performing the tests according to manufacturer instructions. When the glucose test is taken as a serious medical evaluation, good results can follow.
Original posting 7 Sep 1998
Posted to Blood Tests and Insulin Injections
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Last Updated: Tuesday April 06, 2010 15:09:00
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