Glycated haemoglobin; past, present, and future are we ready for the change

Abstract

Glycated haemoglobin has been in use to monitor control of blood glucose in diabetic patients for about three decades. It provides an average blood glucose level during preceding 10-12 weeks. It is a very convenient blood test, can be done in any clinical setting regardless of prandial state. There were thirty different laboratory methods available to measure glycated haemoglobin with significant variability of results on same sample. IFCC developed a new reference method to measure the glycated haemoglobin, and the method is accepted world wide as only valid anchor for the measurement of HbA1c. In 2009 International expert committee recommended the use of HbA1c to diagnose diabetes with a threshold 6.5%. IFCC recommended the use of a new unit, i.e., mmol HbA1c/mol of total haemoglobin in place of percentage. Meanwhile a trial was conducted to find out relationship between average blood glucose and glycated haemoglobin, and a linear regression equation was developed to measure average blood glucose from HbA1c. Using the equation one can calculate average blood glucose from glycated haemoglobin in mmol/mol. This average blood glucose will be reported as "eAG" (estimated average glucose) and it will be used to monitor glucose control as eGFR (estimated glomerular filtration rate) is used to monitor renal function in chronic kidney disease patients. How easy or difficult would it be to abandon a term and a unit, in use for three decades and introducing a new unit (mmol/mol) and even a new term (eAG); only time will tell. Health professionals will need to familiarize with new term and units, they will also have to spend more time with their patients to educate them about new developments.