Diabetes mellitus is a risk factor for atherosclerosis. Changes in the atheromatous plaque are the cause of ischemic heart disease and myocardial infarction. Various articles have shown that HbA1c as an independent risk factor for coronary artery disease (CAD).23-25 Geng et al.26 in his met analysis found association between high HbA1c level and long-term mortality and myocardial infarction among non-diabetic patients.
However, risk for early deaths in non-diabetic patients with CAD was not associated with high level of HbA1c. In his meta-analysis, a total of 18,041 participants were included for the analysis,27-43 which showed a significantly increased risk of long-term mortality in patients with a high HbA1c level than those with a low HbA1c level (OR 1.76, 95%CI 1.44–2.16, P? 1,750mg/dl) SplenomegalyHyperbilirubinemia (>20 mg/dl) Recent blood transfusionUremia Vitamin E ingestionChronic alcoholism Ribavirin and ?- interferonChronic salicylate ingestion Vitamin C ingestionChronic opioid poisoning Lead Poisoning Similarly increase urea in blood, causes formation of carbamyl-hemoglobin and chronic alcohol consumption leads to formation of acetaldehyde-HbA1 compound formation causing falsely elevated HbA1c. 52Hemolytic anemias and splenomegaly are the factors associated with decreased lifespan of RBCs leading to decreased HbA1c level. Ribavirin and ?- interferon may also cause hemolysis of RBCs and subsequently decrease in HbA1c level. Vitamin E ingestion inhibits glycation process.
Depending upon methods of estimation of HbA1c, the value may alter. Hemoglobin variant may be the cause of either falsely elevated HbA1c or decreased HbA1c whether it is done by electrophoresis or chromatography. Similarly, in the patient with Vitamin C ingestion, if the test is performed by chromatography method, HbA1c level is falsely decreased due to due to competitive inhibition of glycosylation.52Anemia is quite common in the patient with chronic kidney diseases.
The role of renal anemia, erythropoietin intake and routine dialysis complicate the evaluation of HbA1c. Recent reports suggest that glycated albumin is a more appropriate test of glycemic control among that patients.56-59CONCLUSIONSince Diabetes Mellitus has multiple complications, early detection and proper management of it may subsequently reduce the economic burden to the society. It also decreases the rate of mortality which occurs due to complications of diabetes mellitus. Since 2011, WHO has included HbA1c as a component of diagnosis criteria for Diabetes mellitus along with FBG and 2-hr postprandial blood glucose level. Since several research articles have pointed false negative rate of HbA1c, exclusion of Diabetes Mellitus should include other tests like FBG, OGTT, 2-hr postprandial blood glucose level, whichever possible. Various complications associated with Diabetes mellitus can be predicted by the routine use of HbA1c value.
Hence, HbA1c has both diagnostic and prognostic significance. However, during the evaluation of patient, limitations of HbA1c should be considered depending upon various methods of its estimation.
