Why Bother to Calibrate?
By David Mendosa
Calibrating or coding a blood glucose meter certainly is a bother. But with most meters it is one of the steps you have to take when you check your blood glucose level.
If the code on your meter differs from that on the test strip vial, your glucose reading might be way off. This could result in an incorrect insulin dosage or other problems.
“Errors in coding can lead to results that are up to 43 percent inaccurate.” So says an ad for the Ascensia Contour meter. That meter is one of the first that doesn’t require coding or calibration.
A reader says she noticed too late that she had miscoded her LifeScan OneTouch Ultra. “I just noticed that my strips are code 10, but my meter is still set at code 2,” she writes. “Have my reading been too low or too high? How much?”
Are her numbers 43 percent too high or too low? Neither customer service nor technical support people at LifeScan could tell us. The key point in a long statement the company provided says that, “If the meter and test strip codes do not match, the test results may be inaccurate and should not be used as the basis of any diabetes self-care treatment decisions.”
But the experience of one endocrinologist practicing in Amarillo, Texas, indicates that the readings in this case might not be far off. “I have experimented with the One Touch meters deliberately miscoding the code number,” Dr. William (Reddy) Biggs tells me. “It did make a slight difference, but usually not enough to cause a change in insulin dose.”
Dr. Biggs estimates that his patients get the code right about 95 percent of the time. The incidence of miscoding is so low, he believes, because his office trains all of his patients on using meter, including coding.
Dr. Alan Rubin, author of Diabetes for Dummies, tells me that his patients don’t have coding problems. “I have all my patients using the Accu-Chek Compact, which automatically codes the meter for the drum of strips currently in it,” he says.
The Accu-Chek Compact and the Ascensia Contour are two meters that completely avoid coding problems. Another is the Ascensia Breeze.
Otherwise, “Bad coding happens all the time,” an expert at Bayer Healthcare, which makes the Contour and the Breeze, tells me. “The miscoding could be way too high or way too low.”
There are other meters that you don’t have to calibrate, according to another endocrinologist who asked not to be quoted by name. He says they are the Ascensia Elite, the Ascensia Elite XL, and Accu-Chek Advantage. The quality control for these strips is so good, he says, that they always have the same code.
You still do have to bother calibrating most meters, and you can’t predict how far off a miscalibrated meter will be. But with these six meters you can forget about it.
Sidebar: Coding in Professional Literature
Reports in the literature suggest that anywhere from 3 to 16 percent of users may have incorrect coding (calibration) on their meters, Dr. Arturo Rolla, a Harvard endocrinologist, tells me.
The largest study found the highest rate of nomatching strip codes, 16 percent. This study included 201 patients at the Diabetes Control Center of Orangeburg, South Carolina. The report appeared last year in Endocrine Practice.
In one suburban California community, of 111 people who had their monitors checked, 9 percent had not calibrated correctly. This was the crux of a poster presented at the Third Annual Diabetes Technology Meeting, 2003.
Across the country in Maine, 116 patients in two practices participated in a study on reported in the January-February 2002 issue of The Journal of the American Board of Family Practice. Here, 97 percent had matched the code on their monitor to the code on the glucose test strip vial.
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NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition.
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