A Tale of Two Glucose Monitors: Which One is Telling the Truth
Accuracy similar across products
By Theresa Garnero, APRN, BC-ADM, MSN, CDE
Q: I just acquired a second glucose monitor just to make sure there is not an error some place. I have used the Accu-check for over a year and just received the Freestyle Lite. The levels from the same blood sample are higher on the Accu-check than on the Freestyle, by as much as 17 points. Both meters test good when using the supplied control solution. Is this something I need to be concerned about?
A. No. Nearly all blood glucose meters have similar accuracy (±15%) when the manufacturer's guidelines are followed providing you are using the same meter.
Let's look at how these systems differ.
(The Accu-check model wasn't indicated, so Aviva is listed for this comparison.)
*Hematrocrit: the amount of red blood cells in the blood. You may see this as "Hct" on your laboratory printout. If you are anemic, or have a hematrocrit outside of this range, your meter results are not considered accurate. Higher hematocrit levels usually result in lower glucose values on a home monitor, and lower hematocrit values result in higher glucose values.
Both of these meters (and most newer ones) read plasma-serum equivalents. Why is this important? The blood from your finger is whole blood. Whole blood consists of red blood cells, white blood cells, and platelets suspended in a protective yellow liquid known as plasma. Glucose can be measured in whole blood, serum, or plasma. Plasma is preferred, as it is the standard when obtaining venipuncture (from the vein) glucose values. In order to keep units of measurement consistent between the laboratory and your home monitors, meter manufacturer automatically convert whole blood samples to a plasma equivalents.
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