I recently saw the following question:
My granddaughter's HgbA1c was elevated to 10. Her glucose readings have been normal. Why does she have this elevated reading?
It seems obvious at first glance that either the elevated HgbA1c is wrong, or the glucose readings are misleading. I'll assume that your granddaughter has a diagnosis of diabetes, and that the glucose readings you describe are being done by her with a home glucose meter, rather than being done in a commercial laboratory. You don't describe her as being a child, teen, or adult, but the issues are mostly age-independent.
As you are aware, the glycosylated hemoglobin test (called by various acronyms including HgbA1c and A1C) has a normal range well below your granddaughter's value of 10. In people without diabetes, the value is usually about 5; for people with diabetes, most endocrinologists would want to see the value below 7. So, based on her value of 10, one would assume there should be lots of elevated blood glucose readings.
There are a few rare conditions where there can be elevated A1C levels with normal glucose levels (with or without diabetes): most of these are due to genetic hemoglobin variants. See a document from the NIH, Sickle Cell Trait and Other Hemoglobinopathies and Diabetes: Important Information for Physicians for more information on this. If this is the case with your granddaughter, the A1C will always be high with some lab methods, but with other lab assay methods, the problem can be bypassed: her physician should discuss this with the laboratory's director.
If your granddaughter has a definite diagnosis of diabetes and all her blood glucose readings are normal, then there's the possibility that either her meter is malfunctioning, or that she doesn't know how to do the testing procedure correctly. Her nurse educator should be able to help figure out if these are issues, and help get them corrected.
There's also a chance that she's fudging the BG results. One way is by choosing when to do the testing - at times when she can assume that the value will be normal. With older meters, there also were ways that people could apply a minimal amount of blood and fool the meter into providing a lower number than the value should have been. And if you don't actually see the results of the meter's memory, there's also the chance that she is verbalizing results that don't match what the meter said. That's always been a common problem with kids with diabetes who want to please parents (and grandparents) and don't quite understand the impact of misleading the adults - but it also can occur with adults misleading spouses or their physicians. This is a psychological problem, of course, and one that most physicians are alert to. If it's a possibility in your family, don't confront the patient directly, but discuss your concern with parents, spouse, or physicians first
There are other possibilities to explain the discrepancy between the A1C and the BG levels: perhaps the elevated A1C represents elevated blood glucose levels two or three months ago, and since then, your granddaughter has done a magnificent job of bringing her BG values under control. In this case, of course, there should be clearly elevated BGs from a few months ago, and a trend of improvement over the past few months.
All in all, it's a difficult situation. I'd suggest that you start off by bringing your concern to a responsible adult, such as her parents, her spouse, or her physician or diabetes nurse educator.
Hope this helps!