Quality Control for Blood Glucose Monitoring

The accuracy—or typically the lack thereof— of blood glucose meters is a big concern of mine. I have written several articles on this topic. But first of all, you have to know if your meter is precise.

At least one of the meter manufacturers recognizes the importance of precision—or at least, they’ve named some of their meters “Precision.” You can buy the Precision Q.I.D. and the Precision Xtra from Abbott Diabetes Care.

But American manufacturers don’t sell any meters called “Accurate.”

A good definition of accuracy is one used by Consumer Reports in its October 2001 evaluation of a few of the meters available at the time. Accuracy, the magazine says, is “how closely the readings agreed with standard lab results.” Researchers also call that concept “validity.”

Consistency, Consumer Reports says, is the “ability to give similar readings on successive tests of the same blood sample.” That concept is known as “precision” or “reliability.” This is in line with the American Heritage Dictionary’s de? nition of precision as “the ability of a measurement to be consistently reproduced.”

Clearly, if you can’t consistently reproduce your blood glucose tests, your meter can’t be correct, except once in a while. Random acts of precision are worse than useless. On the other hand, precision is meaningless if the consistently reproduced result is far from the lab result.

Precision and accuracy are considerations with all devices. But they are of particular concern for our blood glucose meters because our health and treatment depend on them.

Fortunately, it’s not difficult to test the precision of your meter; it’s a bit of a hassle, however, because you need to run at least five measurements in a row on either the same blood specimen or on separate specimens from the same fingerstick.

It is most useful to do the test when your blood glucose level is within your normal range. If the overall variation in blood glucose from your highest reading to your lowest is greater than 5 percent of the average reading, you should view your meter with suspicion.

Q: What if my meter fails the precision test?

If your blood glucose meter doesn’t pass your precision test, you should call the toll-free customer service number that appears on the back of your meter.

If the company is unable to help you resolve the problem with the quality of your meter readings, then you need to try another meter. See page 52-55 of the July 2004 issue of Diabetes Health for a chart of currently available blood glucose meters.

David Mendosa is a freelance journalist and consultant on diabetes. Since 1995, his Web site, www.mendosa.com, has become one of the largest about diabetes. He publishes “Diabetes Update” online each month and is a coauthor of the book “What Makes My Blood Sugar Go Up And Down.”

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