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Re: [IP] Re: testing with uncalibrated strips!

<< >I realized this morning I have been testing at least one or two vials 
 >of strips without realizing the code numbers didn't match the meter's.
 >When I called Lifescan (I use the Ultra) to try to determine how far 
 >off my
 >readings were, the rep said there was no way to know, but that they 
 >indeed incorrect. >>

OK, I generally write the meter column for Diabetes Interview. Sorry I can't 
access the final version, but here's the raw copy for the column that ran in 

Knitters know that, for a perfect match, you need to buy all the yarn for a 
project from the same dye lot to eliminate subtle changes in color that can 
make your solid red sweater come out looking like it has stripes. The reason? 
Minute changes in dyes that cause just the slightest difference in hues of 
the same color.
    It's a similar scenario with the strips you put in your meters to test 
your blood glucose: Minute changes in batches of the chemicals that make up 
the reagents in the strips can cause fluctuations in readings. 
Unlike slightly mismatched yarns, however, mismatched codes between strips 
and meters can cause you to err in correcting your blood glucose. To avoid 
getting an error in your blood-glucose readings, you need to calibrate your 
meter so that it matches the code-or number-stamped on the strip container.
    "All blood-glucose metersb&use whole blood, which is applied directly to 
the reagent," says Edie A. Elkinson of the Chico Chandler Agency in New York 
City, which represents Ascensia. "The reagent itself measures the amount of 
glucose dissolved in the plasma portion of the whole blood. The red cells are 
left on top of the reagent and the liquid plasma with dissolved glucose 
diffuses into the reagent to be measured."
    The reagent is comprised of a mixture of raw ingredients that vary from 
batch to batch. As Elkinson explains, "There is a certain amount of 
manufacturing variability due to raw materials, manufacturing lines and 
environmental conditions. It is very difficult or nearly impossible to 
reproduce the same reagent batches time and time again."
    It's that variance that calls for coding your meter each time you open a 
new box or vial of strips. Some meters include chips to insert, others 
require you to reset numbers on the meter to conform with the code and 
some-including Roche's Compact meter, which has a bar code on the drum of 
strips-calibrates the meter for you.
    When you insert the chip that "tells" the meter what the code is, or 
manually change the numbers on the meter to change the code, "the calibration 
code assigned to a lot of test strips provides an internal adjustment to the 
meter glucose reading algorithm," says Holly Kulp. "This means the strip and 
meter will perform together as a highly accurate system." Kulp is vice 
president of professional relations and customer service for TheraSense of 
Alameda, California. 
    How do companies determine the accuracy of each batch of reagents? They 
test them, using control solutions and, in some cases, whole blood. 
    Roche is one company that tests the solutions using whole blood, in 
addition to using control solutions, says Nancy Lonsinger, director of 
consumer marketing for Roche Diagnostics in Indianapolis, Indiana.
No, Roche does not go to the blood bank to make a withdrawal: It pays people 
to stick their fingers and contribute a drop of blood. Being paid to test? 
What a job!
    Batch-by-batch testing, using both control solutions and whole blood "is 
the best method to correct for small variations rather than a range of 
performance," Lonsinger says. "We uniquely set codes for each lot [and] each 
set of strips is set for a unique code."
    Elkinson says, "studies have shown that most users do not code their 
meters properly or are not aware that this should be done."
    This was borne out by a recent discussion on a diabetes mail list where 
some members believed the code numbers on the strip containers were not 
calibration codes but, rather, indicated the age of the strips: The lower the 
number, the older the strips. Nope. Expiration dates are clearly printed on 
the outside of the box the strips are sold in, as well as on the individual 
    While all of the representatives contacted say errors are generally small 
if the meter is not calibrated to the strip reagent lot, all agree that it is 
important to recode meters that need to have the codes set.
    "There is a potential that readings on the meter may be less accurate," 
Lonsinger says, adding that while result errors may be minimal in most cases, 
"on rare occasions [errors in readings] may be significant."    
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