[Development of the HbA1c international standardization of HbA1c measurement in Japan Diabetes Society].

The International Expert Committee recommends the use of glycated hemoglobin (HbA1c) in diagnosing diabetes mellitus based on updated evidence indicating that HbA1c has several advantages as a marker of chronic hyperglycemia. The Japan Diabetes Society (JDS) has also decided to use HbA1c as one of the criteria of diabetes mellitus after extensive discussion. In this case, however, JDS values are about 0.4% lower than those of NGSP values, which are the global standard, although measurements of HbAlc in Japan are well calibrated with certified serial reference materials from Lot 1 to Lot 4 using a high resolution ion-exchange HPLC method (KO500) and designated comparison method (DCM). The new diagnosis criteria of diabetes mellitus using HbA1c (JDS) > or = 6.1%, which is comparable to NGSP 6.5% was introduced on July 1, 2010. On October 1, 2011, the Reference Material Institute for Clinical Chemistry Standards (ReCCS, Kanagawa, Japan) became certified as an Asian Secondary Reference Laboratory (ASRL) using the KO500 method and the reference materials JCCRM411-2 (JDS Lot 4) after successful completion of NGSP network laboratory certification. Thus, on April 1, 2012, we officially started to use NGSP instead ofJDS values, although the expressions of both NGSP and JDS are used to prevent misunderstanding of the results, for at least certain duration. Finally, on April 1, 2013, HbA1c began to be expressed as NGSP (%) in not only clinical practice but also national specified health checkup systems, and NGSP (%) or IFCC (mmol/mol) or both are used in publications.