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From Buffalo, New York, USA:

My son has had pretty good blood sugar readings on a regular daily basis. There are some highs (above 250 mg/dl [13.9 mmol/L]) every so often especially with his 15-year-old growth hormones kicking in. We were shocked when, at his appointment in September 2010, they told us his A1c was a 12. We did as the doctor asked, sent in all the readings. Based on his blood sugar readings, his A1c should not have been that high. We became very aggressive with insulin and showed even better readings the second appointment, still his A1c showed higher, over 13. This time they checked his pump and gave him a new meter. The blood sugar readings on his meter and his continuous sensor have been showing good numbers AGAIN. I just got results back from the doctor and my son's A1c only showed a drop back to 12 now. The doctors looked at the readings on pump and meter and are confused. The is NO way should my son's A1c be that high; that would mean he is running on average 300 mg/dl [16.7 mmol/L] daily, which is outrageous! I fight with lows more at night than highs at this point. The doctors have no answers for us at this time. They told me they would probably have to admit him and monitor his readings, which would not be under regular normal daily activities for my son. I believe they are under the impression somehow we are not being truthful with readings. As I stated to the doctors, we cannot change the meter readings or change the continuous sensors readings-why would we? My son's life is at stake here and we can't get answers. Have you ever heard of this happening before? I have been in tears and very angry the last three clinic visits as it seems the doctors just won't believe we are not lying. Please help us with any information on finding an answer to this.


I absolutely understand your frustration and that of your diabetes team. I truly doubt that they think you are "lying." But obviously, just like you, they can't but help recognize the discrepancy in the various results!

Unfortunately, as is too often the case, teens do confabulate glucose values and log books and are not always completely forthright and that may make we clinicians a little cynical. And, as parents, we, also, too often believe that our children are precious and can do no wrong! As an adult, you can rationally believe that there would be no reason for your child to be incompletely forthright with the diabetes team. But, teens (and adults) are not always rationale or think to the future. Have YOU always been completely forthright with YOUR doctor? How you ALWAYS stick to your diet and ALWAYS take your medications and ALWAYS exercise daily, etc? Offhand, I can think of a number of ways how a glucometer reading could be manipulated to show a "good" reading (many of these ways I've learned from brilliantly creative young people with diabetes!). I'd have to give some thought as to how the continuous glucose sensor could be manipulated; offhand, this has me stumped.

I have asked around (and online to colleagues) and have gotten very few ideas as to possible ways to manipulate CGMS readings. Two possibilities have occurred:

  1. Similar to testing the blood sugar on a non-diabetic, one could put CGMS on a non-diabetic. But then, one would expect ALL glucose levels to be NORMAL and not mostly acceptable.
  2. One hypothesized that if one were to put a FALSELY low number when calibrating the CGMS, then the CGMS would then read all readings wrongly as "acceptable." But, one would hope that eventually the discrepancy would be recognized by the machine as a calibration error.

Are HbA1c values always correct? Of course not. As with any test, there are false positives and false negatives and inaccurate results due to many possibilities. But for this to have occurred on separate occasions weeks apart would be different, especially if this were the diabetes team's own HbA1c measuring device and they would not getting other discrepant results on other patients.

As we've written on this web site many times, other factors besides glucose influence the HbA1c result, including the quantity and quality of the patient's hemoglobin. It would be extremely rare for some qualitative hemoglobin derangement to manifest after years of normalcy. Quantitative derangements can occur.

So, if your child were my patient, I would do the same thing your diabetes team has planned: put the child in a neutral and safe and controlled environment (like a short-term hospitalization) and see how things correlate between the home glucometer, the hospital results, a new/fresh HbA1c under controlled settings, and maybe even do the glucose sensor. Yes, I concur it is not the home environment but IF everything were confirmed normal in the hospital, then you all could concentrate your efforts to see what is going awry at home.


[Editor's comment: See also a previous question about a fructosamine test to check the A1c resultsSee some of our previous responses on Behavior and A1c, Glycohemoglobin, HgbA1c. In some of these responses, you will see that endocrinologists often recommend that parents take over their teen's diabetes care, in order to ensure that the blood sugars are being checked properly and adequate insulin is being administered. BH]

Original posting 9 May 2011
Posted to A1c, Glycohemoglobin, HgbA1c and Daily Care


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