Is Your A1c Just Another Number?

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Do you consider your A1c just anothernumber? I admit I do not understand people that treat it this wayand ignore what it is telling them and their doctor. One of the peoplein our informal group looks at the A1c just this way. Granted, hiscurrent A1c was a great improvement over his last A1c of 7.3%. He isunexcited with this one and says it is just one more reading. Yes,6.6% is still above the AACE (American Association of ClinicalEndocrinologists) recommendation of 6.5%; and he is still in an areawhere his complications can continue to develop.
When the three of us that were with himasked what number would excite him, his answer was none. He said hedoes not pay attention to the A1c's and only watches his daily bloodglucose readings. He says those are important to him and is worththe extra cost of test strips as he tests as high as nine times aday.
Why do I care? Because I see articleson this almost on a quarterly basis and like this one, they are tooshort and often have missing information. Can the A1c be usedinitially to screen for diabetes? Some doctors do use it forscreening. Other doctors prefer a fasting blood glucose (FBG), the oralglucose tolerance test (OGTT), and the A1c before they will diagnosediabetes. Another test in the diagnosis arsenal is the fastingplasma glucose (FPG) test. Still other doctors will use other teststo make sure it is type 2 and not type 1 or LADA. The C-peptide isalso used to determine insulin resistance or the amount of insulinyour body is producing. Levels of autoantibodies to insulin and thebeta cells can be of some value but even these do not lead to anairtight diagnosis. This is because not all people with type 1 havethese antibodies. Therefore, the diagnosis is still largely aclinical one.
There are others writing about A1ctests. David Mendosa has an explanation I have not seen before andyou can read it here. I was aware that there is a variation in howlong our red blood cells do live and that this can affect our A1creadings. David's blog covers much information that needs to belearned and retained by everyone. Tom Ross blogs about the A1calmost monthly lately by listing some of the search questionsbringing people to his site. They are also very informative and heoften adds some humor. The October blog is here and the Septemberblog is here.  Next we can read Gretchen Becker's blog here about the A1c as she discusses accuracy.
The source that I use and depend on isthe lab tests online dot org website. The reason I like it for myreference is that it covers topics most blogs and articles about theA1c do not even mention. Did you know that the A1c is not reliablefor the following?
1. diagnosis in pregnant women, 2. people who have had recent severe bleeding or blood transfusions, 3. those with chronic kidney, liver disease, or are on dialysis.4. people with blood disorders such as iron-deficiency anemia,vitamin B12 anemia, and hemoglobin variants.
“Only A1ctests that have been referenced to an accepted laboratory method(standardized) should be used for diagnostic or screening purposes.” Too many doctors tend to ignorethis statement and diagnose anyway. This begs the question of whatdoctors are thinking when an A1c test results in excess of 7.0% andyou are only given this statement, “Be care what you eat as yourblood sugar is a little high.” Oh really – do they think theyare being kind when they don't schedule you for more tests or haveyou return another day for the other tests to check if you are aperson with diabetes. Any A1c over 7.0% should require more testingto determine if you have diabetes.
Other facts you may be wise to know: 1. The A1c test will not reflect temporary, acute blood glucoseincreases or decreases. The glucose swings of someone who has"brittle" diabetes will not be reflected in the A1c.2. If you have a hemoglobin variant, such as sickle cell hemoglobin(hemoglobin S), you will have a decreased amount of hemoglobin A. This may limit the usefulness of the A1c test in diagnosing and/ormonitoring your diabetes. 3. If you have anemia, hemolysis, or heavy bleeding, your testresults may be falsely low. 4. If you are iron deficient, you may have an increased A1cmeasurement. 5. If you have had a recent transfusion, then your A1c will befalsely increased (blood preservative solutions contain high glucoselevels) and not accurately reflect your glucose control for 2 to 3months.
The following formula ADAG (A1c-DerivedAverage Glucose) is used to calculate your estimated Average Glucose(eAG) from your A1c result. 28.7 X A1c – 46.7 = eAGAn example of this is an A1c of 6%.The calculation for this would be: 28.7 X 6 – 46.7 = 126 mg/dlfor an estimated average glucose of 126mg/dl. I repeat this is an estimated average because your bloodglucose readings from your meter will generally not be close to thisaverage. The variance is due to the timing of your meter readingsand will not reflect an average.
What this means is that for every onepercent that your A1c goes up, it is equivalent to your averageglucose going up by about 29 mg/dl. For a printable chart conversiontable for eAG click on this link.