Glycosylated Hemoglobin: a literature review

Abstract

Recently, a minor component of normal adult hemoglobin has been discovered. This hemoglobin is referred to as glycohemoglobin or Hgb AI, and it is made up of subgroups A-E (Hgb AIA-AIE). As the name implies, these hemoglobins are simply Hgb A with a hexose residue attached to each of the beta chains. The most important of the subgroups is Hgb AIC wich has a glucose molecule attached to the beta chains. The degree of glycosylation of Hgb A is directly dependent upon the concentration of blood glucose. Hgb AIC and total glycohemoglobin levels have been found to be two to three times greater in diabetics than in nondiabetics. It has also been determined that Hgb AIC and glycohemoglobin levels are reduced to near normal values when the blood glucose is well controlled. Since glycosylated hemoglobin levels represent a time-averaged blood glucose level, it is considered to be a better indicator of control than individual blood glucose levels. The glycohemoglobins are eluted quite easily before the major Hgb A component on ion exchange columns. Although Hgb AIC can be isolated by column exchange, most methods separate total glycohemoglobins, not just Hgb AIC. Thus, glycohemoblobin levels by ion exchange column separation may become the test of choice in monitoring treatment of diabetes mellitus.