UTILITY OF HBA1C IN THE PROGNOSIS OF DIABETES MELLITUS
Suman Bagchi
1*,Omprakash Patel
21Assistant professor, department of forensic medicine & toxicology, C.L.Chouksey memorial homoeopathic medical college, hospital & research center Bilaspur , Chattishgarh, 2Assistant professor, department of pharmacy. C.L.Chouksey memorial homoeopathic medical college, hospital & research center, Bilaspur ,
Chattishgarh. Email: dr.sbagchi@gmail.com.
Received -13-01-2014; Reviewed and accepted -25-01-2014
ABSTRACT
Diabetes mellitus is not a single disease entity but rather a group of metabolic disorders sharing the common underlying feature of hyperglycemia.The morbidity associated with long-standing diabetes of either type (Type I and Type II) results from several serious complications. The pathogenesis of the long-term complications of diabetes is
multifactorial, although persistent hyperglycemia (“glucotoxicity”) seems to be a key mediator.1 Much of the evidence supporting a role for glycemic control in ameliorating the
long-term complications of diabetes has come from large randomized trials.2 The assessment of glycemic control in these trials has been based on the percentage of
glycosylated hemoglobin, also known as HbA1C. The American Dietetic Association recommends that HbA1C be maintained below 7% in diabetic patients. Following
widespread recognition that sustained hyperglycaemia is an important determinant of the long term complication 3,4, there has been renewed interest in monitoring Control of
diabetes5.The discovery of glycosylated haemoglobin has therefore been timely,measurement of it should allow more objective assessment of control.
Key words: :Diabetes mellitus, HbA1c.
INTRODUCTION
The glycosylated haemoglobins are becoming accepted as a measure of longterm glycemic control in diabetes mellitus.The term HbA1c refers to glycated haemoglobin.It develops when
haemoglobin joins with glucose in the blood, becoming “glycated”. Rahbar 5 first discovered the association of increased HbA1c levels
with diabetes mellitus in 1968.By measuring glycated haemoglobin (HbA1c),clinicians are able to get an overall picture of
what our average blood sugar levels have been over a period of weeks/months.For people with diabetes this is important as the higher the HbA1c,the greater the risk of developing diabetes-
related complications.
Glycosylated haemoglobins are the result of simple chemical reaction between haemoglobin and sugars after synthesis of haemoglobin is complete-that is post- translation modifications.
The reaction proceeds in two stages:, enzymes are not involved.6,7
1. Glucose combines with the α-amino acid group of the valine residue at the N-terminus of β-globin chains to form an aldimine compound (schiff base).The reaction is reversible, and dissociation to native haemoglobin and glucose occurs readily.
2. Internal rearrangement of the aldimine intermediate by the Amadori reaction yields a stable ketoamine derivative.
When the body processes sugar,glucose in the blood stream naturally attaches to haemoglobin.The amount of glucose that combines with this protein is directly proportional to the total amount of sugar that is in your system at that time.
Because red blood cells in the human body survive for 8-12 weeks before renewal8,measuring glycated haemoglobin (or HbA1c) can be used to reflect average blood glucose levels over
that duration,providing a useful longer-term gauge of blood glucose control.
Current use of HbA1c :
Monitor long term glycemic control
Assess the quality of diabetes care.
Predict the risk for the development of complications. A patient is diabetic if he has an increased HbA1c and
an increased fasting plasma glucose concentration.10,11
Current HbA1c recommendations 9
Normal IDF ADA AACE
A1c <6% <6.5% <7% <6.5% Preprandial <100 <110 90-130 <110 Postprandial <140 <155 <180 <140
IDF— International Diabetes Fedaration. ADA— American Diabetes Association.
AACE— American Association of Clinican Endocrinologist.
If your blood sugar levels have been high in recent weeks,your HbA1c will also be greater.
Advantages of HbA1c for the diagnosis of Diabetes mellitus:12
Several researchers13-15 have investigated the possibility of using glycosylated haemoglobin measurements in diagnosis of diabetes mellitus.The advantage of using glycosylated haemoglobin would be—
Only a single blood sample would be requirred. Fewer factors influence glycosylated haemoglobin
levels than affect the glucose tolerance test.
HbA1c correlates with retinopathy.There is a stronger
correlation between HbA1c and retinopathy than
between fasting glucose levels and retinopathy. [ 2009-International Expert Committee Report of the A1c Assay in
the diagnosis of Diabetes.Recommends that hba1c be adopted as one of the diagnostic criteria for Diabetes.(Diabetes Care,Vol-32,Number 7,July-2009)]
HbA1c measurement can be used to differentiate
Bagchi et al Mintage journal of Pharmaceutical & Medical Sciencesǀ20-21
Vol 3 Suppl 2, Feb 2014 www.mintagejournals.com 21
differentiates these patients from large proportion of patients who have hyperglycemia due to stress secondary to infarct.16
2010 Consensus Statement on the Worldwide
Standardization of the HbA1c Measurement:
HbA1c test results should be standerdized Worldwide.
The IFCC reference system for HbA1c represents the only
valid anchor to implement standardization.
HbA1c results are to be reported by clinical laboratories
Worldwide in SI units (mmol/mol,no decimals) and derived NGSP Units (%,one decimal).(diabetes care,vol-33,number 8,july-2010)
HbA1c related with pregnancy:
Certainly HbA1c concentrations during pregnancy show a positive
correlation with birth weight (Corrected for gastational age) which is consistent with established experience that large babies are associated with poorly controlled diabetes.17
CONCLUSION:
The recent availability of glycosylated haemoglobin measurement has provided a valuable tool in the diagnosis and measurement of diabetes mellitus.This objective test allows for more reliable assessment of diabetic control than any other parameter.Along with, the physician should also be aware that there are certain clinical conditions which can lead to inappropriate results,like-Uremia,Iron deficiency anaemia,Haemolytic anaemia,HbF,HbS.
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