January 23, 2004
A1c (Glycohemoglobin, HgbA1c)
Question from Peoria, Illinois, USA:
I was wondering if when an HbA1c is checked, does it make a difference if the hands are clean (i.e., no residue of sugar)? In our clinic a week ago we have a patient that was amazed his A1c went up and wanted it rechecked. He had just eaten a hamburger and fries from Hardees. When we rechecked it, there was over a 1% point difference. Was this purely a coincidence?
Answer:
HbA1c assays are not affected by glucose contamination of the skin. However it is important to remember that the 95% confidence limits of the assay even using a reliable instrument like the DCA 2000, and with one person in a unit doing all the assays, can be as high as +/- 8%. This means that a 1% difference between two successive readings on the same person does not necessarily imply significant clinical change or technical error. What it does mean though is that the results always have to be interpreted in relation to an imagined regression line drawn through a significant number of previous results.
DOB
