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Home testing BG and Lab result

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paul_melb

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While I know there is a margin of error on home testing meters, I got a good idea of it today when I used my meter at exactly the same time the nurse drew blood for the professional FBG test . My meter showed 5.7, hospital 5.2. I don't know if it is usual for home meters to show higher readings. A 10% difference doesn't seem to bad, particularly as the lab result was lower. This was an AccuChek Performa after a 13 hour fast ( without morning Metformin).
cheers
paul
 
Did you actually test the same blood? Venous blood and capillary blood may have different blood glucose concentrations and the difference between them seems to vary between individuals.

Unfortunately, empirical conversion factors have been applied to generate equivalent glucose values for different blood sample compartments without adequate data to show equivalence. One such conversion is that fingerstick capillary blood has a glucose concentration that is 7-8% higher than the concurrently drawn venous concentration[11]. Others have presented charts showing the equivalence of venous and capillary glucose levels that differ between 0% to 13% depending on the glucose level[12]. The validity of these conversion factors has been called into question since individual differences between capillary and venous blood glucose values are too great to allow for a meaningful transformation to be applied
Click to expand...
http://www.bestthinking.com/articles/me ... nous-blood
 
Oh, good point. Not the same blood, just the same time. But I thought most if not all meters are callibrated to allow for the difference you mention? If not then the difference could be 15-20%
cheers
 
paul_melb said:
Oh, good point. Not the same blood, just the same time. But I thought most if not all meters are callibrated to allow for the difference you mention? If not then the difference could be 15-20%
cheers
Click to expand...
No the calibration is to allow for difference between plasma capilliary and whole blood capilliary not venous plasma and capillary plasma
Using the same blood wouldn't work either according to Gretchen Becker since home meters depend on oxygenated blood and venous blood is not oxygenated!
But the differences between the 2 are less at fasting than post prandial in any case.
What you can take from your test is that your meter seems to be reasonably close to the lab reading (when fasting) ... now just to check that it's precise ie that it gives similar readings one after another!
 
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