The Diabetes Control and Complications Trial (DCCT) has demonstrated that HbA1c is an indicator for the development of diabetes . The National Glycohemoglobin Standardization Program (NGSP) has introduced a standardization based on the DCCT reference method improving the inter-laboratory comparability of HbA1c .
The IFCC Working Group on HbA1c Standardization prepared primary reference materials and developed a reference method for HbA1c. According to the consensus agreement of international and national diabetes associations from May 2007 , all IVD manufacturers should implement traceability to the IFCC reference system for HbA1c. In future, IFCC results should be reported in mmol/mol (SI unit) and NGSP units in % using the IFCC-NGSP master equation.