Whats the cause of elevated Hba1c in hyperglycemia?

Question

Whats the cause of elevated Hba1c in hyperglycemia?

Answer 1

One of the many dangers of having a chronically high blood glucose level is that proteins get glycoylated (a glucose gets 'added' to them).  This can affect the protein's function, and this glycosylation is believed to be a major factor in explaining why uncontrolled diabetes is so bad for you.

HbA1c is just one of these many glycosylated proteins - it's actually your haemoglobin molecule that's had glucose added to it.  The higher the blood glucose level, the more proteins are glycosylated, and so the higher the HbA1c.  Since the process is irreversible, and since haemoglobin hangs around inside a red blood cell for about 120 days, the HbA1c is a good measure of CHRONIC (over the last 2-3 months) glucose control.

Answer 2

Hba1c means glycated haemoglobin, where the proteins on the haemoglobin are glycated (bound to glucose) in the blood. An elevated Hba1c indicates the amount of glucose present and the duration of exposure of the haemoglobin to glucose.

Hba1c provides an indication of average glucose reading preceding 2 to 3 months (the life span of the haemoglobin). Hba1c can be measured at any time and levels are not normally affected by acute changes in therapy or diet.

Therefore it is not what causes the elevation of Hba1c in hyperglycaemia, it is more the case of hyperglycaemia causing an elevation of Hba1c.