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I am 57 years old and have been taking insulin for 52 years. Given that a meter glucose reading has a 10 to 15% margin of error at best, does this mean that if a venous blood sample were taken at the same time as a finger capillary sample, the comparison between the two readings would lie somewhere within the margin of error?

I can speak personally when I write that meter readings taken within seconds of one another from fingers and from forearms bear a noticeable difference from one another. I have read that there has been more than one study to support this contention. It appears, at least with some people, that forearm readings lag about half an hour behind finger readings.


The recent report by Geoff McGarraugh and others confirms that the forearm blood sugar measurement can lag behind the finger tip assay, but points out that this is a blood flow issue which can be eliminated by vigorously rubbing the forearm skin before sampling. Without going into statistical terminology, the chance that two essentially identical samples would fall within the same 95% confidence limits would be slightly less, i.e.about 90%. See Glucose Measurement Using Blood Extracted from the Forearm and the Finger . (Note: You will need Adobe Acrobat to open it.)


Original posting 3 Oct 2001
Posted to Blood Tests and Insulin Injections


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Last Updated: Tuesday April 06, 2010 15:09:26
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