I was at ADA recently and there was a heightened presence of A1c testing as a tool in the diabetes kit this year. Everyone assumes that a measurement of A1c = a measurement of historical glucose which is not entirely correct. Further, hemoglobin makeup has the potential to change every few years so it’s not even measurable on the same scale within the same person unless you get your A1c on a frequent basis.

There was an initiative announced that is trying to finalize an international standard which takes % hemoglobin A1c from any test method and recalculates it into mean blood glucose along the same lines as what you see on your blood glucose meter. The thought being that patients don’t understand the A1c number and that they do understand the meter based scale. A bigger problem is the presumption that you can simply change from presenting patients with a % A1c vs. a formula translation into mean blood glucose. A1c is only a measure of the glucose left over within a small fraction of your hemoglobin A and then only within the 1c and not 1d, etc… assuming that everyone has the same hemoglobin signature…which is entirely not true. The most common forms of A1c testing (DCA2000 in office and laboratory venipunctures) cannot detect these variants and therefore the oh, so often questioning if the A1c result is correct is entirely warranted.

This same attitude of ‘good enough’ has also contributed to physicians basing clinical decisions on poor quality data and when that involves the A1c, for many people the only data point available for determining therapy effectiveness and decisions, we end up with situations that confuse and confound both physician and patient (lack of screening, inaccurate A1c test methods and imprecise analysis).

For patients in our healthcordia programs we share both A1c and its calculated average but they are both just numbers. The real utility however is first screening for the abnormal hemoglobins using our HomeCheck combination hemoglobin screening + A1c laboratory analysis and then identifying the increase or decrease in a highly accurate A1c/MBG.

The timing of checking for average blood glucose is probably a bigger issue since approximately half of the A1c is based on the immediately preceding 30 days. Therefore, unless you check bg’s with your meter around the clock, you still don’t have a good measurement reflecting patient actions and therapy effectiveness given that lifestyle changes usually do not occur 30 days prior to your doctor visit A1c checks. Bottom line is nobody knows what they’re really measuring which is making it hard to understand and patient actions are not getting accurate feedback from which to encourage or reinforce.

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This entry was posted on Monday, July 2nd, 2007 at 10:06 am and is filed under A1c, Accuracy & Precision, Clinical, New Products. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.