Diabetes mellitus: the long way of standardization of HbA(1c) to the level of highest metrological order.

Glycated haemoglobin (HbA(1c)) measurements are used in clinical studies and for the management of diabetic patients. Various efforts were made to standardize the HbA(1c) measurements with consensus standards and standards based on a reference measurement procedure with external calibration. According to ISO 17511 a standard should meet highest accuracy possible, have a defined uncertainty of measurement and the calibration should be traceable to SI units. For HbA(1c) this has been realized using a LC-ID-MS procedure based on the existing reference measurement procedure.