Glycated hemoglobins

Hb A with fructoseA, 6-diphosphate attached to the N-terniinal of the P-chain  

Hb A with glucose-6-phosphate attached to the N-terminal of the p-chain Comprises Hb A i and Hb Aja2 

Hb A with pyruvic acid attached to the N-terminal of the P-chain Hb A with glucose attached to the N-terminal valine of the P-chain Unstable Schiff base (aldimine) a labile intermediary component in the formation ofHbAic. 

GHb has been firmly established as an index of long-term blood glucose concentrations and as a measure of the risk for the development of complications in patients with diabetes mellitus. GHb was a cornerstone of the DCCT. (To prevent assay variability [see section on assay standardization later in this chapter], all GHb assays in the DCCT were done in a central laboratory that measured Hb Aj by HPLC.) The DCCT documented that there is a direct relationship between blood glucose concentrations (assessed by 

Hb Ale) and the risk of complications. The absolute risks of retinopathy and nephropathy were directly proportional to the mean Hb Ai. The risk of retinopathy increased continuously with increasing HbAi and a single measure of Hb Ale predicted the progression of retinopathy 4 years later. In fact, subsequent analysis revealed that the mean Hb Aic was the dominant predictor of retinopathy progression, and a 10% lower Hb Aic concentration was associated with a 45% lower risk. The risk of microvascular complications varies continuously with Hb Ai and there is not an Hb Ai concentration below which the risk is eliminated. 

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Keywords Reference networks Standardization Lipids Lipoproteins Glycated hemoglobin... 

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 12-12 Extract of data from Distribution 257 of the UK NEQAS for Glycated Hemoglobin, May 2003. (Courtesy Dr.J. Middle, UK NEQAS.)...

Agency for Healthcare Research and Quality. Evidence Report/Technology Assessment No. 84, Use of glycated hemoglobin and microalbuminuria in the monitoring of diabetes mellitus. 2003. Available at www.ahrq.gov... 

A commercial assay is performed on an automated analyzer that uses a soluble reagent consisting of dihydroxy-boronate coupled to high molecular weight polyacrylic acid. GHb binds to the boronate. The polyanionic-glycated hemoglobin affinity complex attaches by electro-... 

Removal of Labile Glycated Hemoglobin from Red Blood Cells... 

DCCT. Feasibility of centralized measurements of glycated hemoglobin in the Diabetes Control and Complications Trial a multicenter study. Clin Chem 1987 33 2267-71. 

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