January 12, 2005
A1c (Glycohemoglobin, HgbA1c)
Question from Rockford, Illinois, USA:
My son has had type 1 for about four years. Since diagnosis, his A1cs have gone from in the 6s the first year, mid 7s for the next two years,and from 8-8.5 this last year. Most recently, in October 2004, his A1c was 8.3. He has been pumping for just over a year. All of the A1cs in the 8-8.5 range have been since he started using a pump.
Generally speaking, I feel he is in pretty good control even though his A1cs do not reflect this. I’m always a little shocked when his laboratory tests are reported. Even though our diabetes team would like his A1c below 8, they did not offer many suggestions to gain better control. In frustration, I took my son to another endocrinologist at the University of Wisconsin. At his appointment, which was in early December, they did an A1c at the office visit and it was 7.5. I was thrilled and the physician was confident that “office A1c” was accurate and matched the regular laboratory. He made a few changes to both basal and bolus rates and my son has had excellent control since his visit. I kept our scheduled appointment with our local endocrinologist and just got our test results back. His A1c is 8.3 again! Is it normal for that much variation between laboratories? Generally, are the “office” tests accurate? My son did have some crazy numbers on Christmas Eve and Christmas Day; we couldn’t keep up with all he consumed! Certainly, a few days with high numbers so close to blood work wouldn’t have that great of impact would they?
Answer:
Your question is really about the standards for the test, I think. I do know that different laboratories have different standards, and the same laboratory may change standards over time. This can lead to confusion and sometimes frustration if you don’t know things have changed.
Diabetes control gets harder over time as the pancreas is destroyed. I see rises in A1cs, too. I, generally, wouldn’t be disappointed by an 8.3 in a six year old.
The office tests are generally very accurate, so good that they are given a special status by the testing authorities. I would expect the test was correct in the office and likely correct in the laboratory, too, just different standards. Since I know the office standard and don’t know the laboratory standard, I would be very happy with the 7.5.
LD
