Significance of HbA1c Test in Diagnosis of Diabetic patients

 

 Significance of HbA1c Test in Diagnosis 

and Prognosis of Diabetic Patients

Diabetes is a global endemic with rapidly increasing prevalence in both developing and developed countries. The American Diabetes Association has recommended glycated hemoglobin (HbA1c) as a possible substitute to fasting blood glucose for diagnosis of diabetes. HbA1c is an important indicator of long-term glycemic control with the ability to reflect the cumulative glycemic history of the preceding two to three months.

 HbA1c not only provides a reliable measure of chronic hyperglycemia but also correlates well with 

the risk of long-term diabetes complications.

 Elevated HbA1c has also been regarded as an independent risk factor for coronary heart disease and stroke

 in subjects with or without diabetes. 

The valuable information provided by 

a single HbA1c test has rendered it as a reliable

 biomarker for the diagnosis and prognosis of diabetes. 

This review highlights the role of HbA1c in diagnosis and prognosis of diabetes 

Introduction

Analysis of glycated hemoglobin (HbA1c) in blood provides evidence about an individual’s average blood glucose levels during the previous two to three months, which is the predicted half-life of red blood cells (RBCs).1 

The HbA1c is now recommended as a standard 

of care (SOC) for testing and monitoring diabetes,

 specifically the type 2 diabetes.2 

Historically, HbA1c was first isolated

 by Huisman et al.3 in 1958 and 

characterized by Bookchin and Gallop4 in 1968, 

as a glycoprotein. The elevated levels of HbA1c in diabetic patients were reported by Rahbar et al.5 in 1969. 

Bunn et al.6 identified the pathway leading to the formation of HbA1c in 1975. Using the HbA1c as a biomarker for monitoring the levels of glucose among diabetic patients was first proposed by Koenig et al.7 in 1976.

Proteins are frequently glycated during various enzymatic reactions when the conditions are physiologically favorable. However, in the case of

 hemoglobin, the glycation occurs by

 the nonenzymatic reaction between

 the glucose and the N-terminal end of the

 β-chain, which forms a Schiff base.8,9 During the rearrangement, the Schiff base is converted into Amadori products, of which the best known is HbA1c (Fig. 1). 

In the primary step of glycated hemoglobin formation, hemoglobin and the blood glucose interact to form aldimine in a reversible reaction. In the secondary step, which is irreversible, aldimine is gradually converted into the stable ketoamine form.10 The major sites of hemoglobin glycosylation,

  About 6% of total HbA is termed HbA1, which in turn is made up of HbA1a1, HbA1a2, HbA1b, and HbA1c fractions, defined by their electrophoretic and chromatographic properties. 

HbA1c is the most abundant of these fractions and in health comprises approximately 5% of the total HbA fraction. 

Ref

Biomark Insights. 2016 Jul 3;11:95–104. doi: 10.4137/BMI.S38440

Significance of HbA1c Test in Diagnosis and Prognosis of Diabetic Patients

Shariq I Sherwani 1, Haseeb A Khan 2,✉, Aishah Ekhzaimy 3, Afshan Masood 4, Meena K Sakharkar 5tients.