Q: I just noticed that my strips are code 10, but I forgot to change my meter, which is still set at code 2. My meter is a LifeScan OneTouch Ultra. I don’t know how many bottles of strips I have gone through at this wrong setting.
Have my readings been too low, or too high? And by how much have they been off?
A: 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 in this magazine for the Ascensia Contour meter. That meter is one of the first that doesn’t require the user to code the meter.
Neither customer service nor technical support people at LifeScan could tell us how far off your readings might have been. The key point in a long statement provided by the company is, “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 OneTouch meters, deliberately miscoding the code number,” says William (Reddy) Biggs, MD. “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 in using the meter, including coding.
Alan Rubin, MD, 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, the Ascensia Contour and the Ascensia Breeze are three meters that prevent any coding problems by coding automatically.
Otherwise, “bad coding happens all the time,” says one expert at Bayer Healthcare, which manufactures the Ascensia Contour and Breeze meters.
You still have to code most meters, and you can’t predict how far off a miscoded meter might be.
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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, says Harvard endocrinologist Arturo Rolla, MD.
The largest study found the highest rate of non-matching 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 subject of a poster presented at the Third Annual Diabetes Technology Meeting in 2003.
Across the country in Maine, 116 patients in two practices participated in a study 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.