GLYCATED HEMOGLOBIN STRUCTURE AND SYNTHESIS OF MOLECULE: Glycated hemoglobin A1c, the major fraction of glycated hemoglobin, is formed by irreversible nonenzymatic glycation. Its concentration depends only on the life span of red blood cells and blood glucose levels. CLINICAL SIGNIFICANCE OF GLYCATED HEMOGLOBIN A1c: It is the key parameter for monitoring the regulation of diabetes and for assessing the risk of microvascular complications. It is a diagnostic criterion for diabetes as well. Its concentration reflects the average value of blood glucose over the last two to three months. The estimated average glucose, a new parameter which facilitates the patient's self-monitoring of diabetes, can be calculated from its value. METHODS FOR DETERMINING GLYCATED HEMOGLOBIN A1c AND THEIR STANDARDIZATION: Immunoassay and ion-exchange chromatography are commonly used methods for the glycated hemoglobin determination in routine laboratory practice. The advantage of immunoassay is that there is no need for the sample pre-treatment in order to eliminate unstable glycated hemoglobin A1c intermediary forms, and the possibility of false positive results is lower. The current program of standardization requires traceability to the International Federation of Clinical Chemistry and Laboratory Medicine reference method. REPORTING AND INTERPRETATION OF RESULTS OF GLYCATED HEMOGLOBIN A1c DETERMINATION: Glycated Hemoglobin A1c can be reported as % or as mmol/mol. In our country, it is recommended to use the International Federation of Clinical Chemistry and Laboratory Medicine units (mmol/mol). When interpreting the results, the potential causes of falsely high or low values must always be taken into consideration.
Recommendations for clinical practice: Periodic determinations of glycated hemoglobin A1c are recommended for monitoring of diabetes regulation. Additionally, the determination is recommended for the diagnosis of diabetes. The target value for the prevention of microvascular complications is < 7% and the diagnostic criterion for diabetes is 6.5%.