HbAlc, glycated

Tahara Y, Shima K. Kinetics of HbAlc, glycated albumin, and fructosamine and analysis of their weight functions against preceding plasma glucose level. Diabetes Care 1995 18 440-7. 

The National Glycohemoglobin Standardization Program (NGSP) used the CRMLN model to establish a reference laboratory network to standardize glycated hemoglobin (i.e., HbAlc) [33, 34], The purpose of the NGSP is to standardize HbAlc so that clinical laboratory results are comparable to the Diabetes Control and Complications Trial (DCCT) where relationships were established to mean blood glucose and risk for vascular complications. 

Figure 32-1. (A) Schematic representation of the nonenzymatic glycation of proteins, including hemoglobin, resulting in glycated HbAlc. (B) Chemical structure of advanced glycation end products in tissues exposed to chronic hyperglycemia.The R groups designate tissue proteins that have become cross-linked and frequently become dysfunctional as a result of this process. Adapted from Brownlee (1992).

US guidelines are to have an HbAlc of less than 7.5%. Long-term damage caused by protein glycation includes ulcers, kidney failure, blindness, strokes and ischaemic heart disease. 

Figure 5-8 CE-based identification of uncommon hemoglobin (Hb) variants by clEF. Analysis of blood from a patient with Hb S/Aida trait detected the presence of seven different normal and abnormal structural Hb variants, some of which are not detectable by conventional electrophoresis because of a lack of sensitivity or inadequate resolution.The four abnormal variants include Hb S, Aida, S/Aida hybrid, and A2/Aida. Identifying a-variants of Hb A by cfEF helps discriminate between a- and b-globin gene mutations in samples containing unknown Hb variants. Glycated HbA (HbAlc) is also apparent in the electropherogram.

Figure 2. Past HbAlc in blood and glycated protein distribution in hair.

The distribution of glycated protein in hair and HbAic in blood over several months is shown in Fig 2. As the results show, it seems to be possible to evaluate past states of diabetes mellitus. The good correlation between these two tests suggests that the proposed method could be useful in monitoring of diabetes mellitus as an alternative to HbAlc in blood. 

Another cUnical utility for Hb is in quantitation of HbAlc. HbAlc results from glucose binding with Hb via a non-enzymatic reaction (the Amadori rearrangement), to form a stable, glycated Hb. HbAlc is one of the best indicators for monitoring the status of diabetes control, and its clinical measurement has been recommended, by the American Diabetes Association, for patients. Glucose itself is a small, low-molecular-weight molecule, and when... 

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