May 21, 2008 By Meredith Fairbank for Diabetes1
The 21st century will herald the advent of new useful gadgets for diabetics, including a cool Dick Tracy watch that measures glucose levels. But while blood glucose meters are constantly evolving, know that they have a number of limitations.
Proper Usage of Glucose Meters
The margin of error for blood glucose meters is ±10-15 % when used properly. Errors, however, can drastically affect the results.
Be sure there is no dirt or dust on the meter, that test strips are not too old, and that the blood sample size is right. Also be aware that humidity, extremes in temperature, and the presence of drugs in your bloodstream can affect the results. Talk to your doctor about these and other things to watch for that may impact your testing.
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Checklist for proper usage of glucose meters:
Accurate calibration and coding
Temperature and humidity
Presence of dirt or dust
Sufficient blood sample
Test strips that are not too old and not counterfeit
Presence of certain drugs in bloodstream
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Most meters, unless you’re using a meter that requires no coding (Two such meters are: Abbott's Freestyle Freedom Lite and Bayer’s No Coding Technology) must be calibrated. To accurately calibrate the meter, enter the code that may be found on the vial of test strips, or enter a chip that comes with the strip. Entering the coding or chip into the glucose meter will calibrate it to that particular batch of test strips. Miscoded meters can place patients at increased risk of hypoglycemia.
The A1cNow Meter Gives Inaccurate Readings for Children
The portable A1cNow device by Metrika has been found to give inaccurate readings for children with type 1 diabetes. Even when administered by medical professionals the test results produced by this meter were found to be inaccurate. The monitor measures glucose levels over the last few months rather than over the last few hours like most devices.
The manufacturer is not kidding when it states that it makes no guarantee of the accuracy of the results obtained by this device.
For Kidney Dialysis Patients with Diabetes
In a recent study, diabetic kidney hemodialysis patients were found to have higher glucose levels than standard HbA1c tests indicate. This may occur if red blood cells are depleted in hemodialysis patients since the test measures the hemoglobin in the red blood cells that have reacted with glucose.
Further research must be done to determine whether these findings apply to patients on peritoneal dialysis and patients with kidney disease who are not on dialysis.
The report recommends that GA (glycated albumin) testing (not yet available in the U.S.) be used instead for dialysis patients because it measures the amount of blood sugar that has reacted with albumin, a plasma protein, instead of the hemoglobin. The study was supported by Asahi Kasei Pharma Corporation, Tokyo, Japan, the manufacturers of the GA test.
Counterfeit Test Strips
In 2006, the FDA reported that LifeScan was voluntarily recalling test strips that were found to be counterfeit. Updates on the exact lot numbers and brands can be found at lifescan.com and within the FDA’s MedWatch program report. Fake test strips do not give accurate readings, should not be used, and should be reported immediately.
Although this problem appears to have been solved it is worth remembering that problems of this nature can occur.
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