Poor glucose control

Glycosylation of hemoglobin, and other proteins, takes place over time. That is why concentration of glycosylated hemoglobin is used to determine whether high blood sugar level seen in other tests is recent or has been present for a long time. To put it simply, if a patient has a high glucose level, you cannot tell whether it is a problem, or it is just that the person has eaten a while back. On the other hand, if the glycosylated hemoglobin level is high, you know for sure it is a long-term problem.

HgA1C or HbA1c is an abbreviation for glycosylated hemoglobin. It's a measure of blood sugar levels over the last three months.