January 10, 2003
A1c (Glycohemoglobin, HgbA1c), Blood Tests and Insulin Injections
Question from Centreville, Virginia, USA:
We just returned from our 12 year old daughter’s checkup. Her A1c was 9.0%, and she has had the same result for the last three tests, no matter what we do to improve the numbers. Her endocrinologist believes that she is cheating her meter (One Touch Ultra) because her actual daily numbers should represent a much lower A1c. The doctor says she needs counseling from a group support and probably from a psychologist. Are there any other possibilities that will produce high A1c numbers? Can you cheat information on a One Touch Ultra and how? If there is, what meters do you recommend instead.
It is difficult (though not impossible) to cheat on the numbers of any meter, but there are some considerations that you probably already know: An appropriate amount of blood needs to be on the strip; too little can give a falsely low reading. The skin should be dry and without residual alcohol or soap/water. Again, you do not want to “dilute” the sample. This is a matter of technique and some folks have tried to “persuade” the meter to give lower readings this way. Previous studies do suggest to use brand name strips for the meters (rather than generic strips) for more consistently accurate readings.
The hemoglobin A1c value is influenced not only by the amount of glucose available, but also the quantity and quantity of hemoglobin available. Certain, fairly unusual, irregularities of hemoglobin can lead to false HbA1c values so this could be explored.
These statements should not detract from the fact that the much more common cause of elevated HbA1c values is sub-optimally controlled diabetes. The glucose checks using the One Touch� Ultra meter (which takes five seconds) are probably being done four to six times a day, but there are 1440 minutes (86,400 seconds) during a day. What’s happening all those other times when you don’t check for glucose -say during sleep? Some patients have nicely developed an eating and activity schedule with their insulin that allows reasonable checks at meal times but not between meals. So check a few two-hour after meal glucose checks, and do not be surprised if on really closer inspection, you find that the meals eats are actually a bit more generous than her meal plan would call for.