Relationship between NGSP and JDS HbA1c numbers

Abstract

The aim of this investigation is to examine the correlation between the HbA1c numbers used by the National Glycohemoglobin Standardization Program (NGSP) and the Japan Diabetes Society (JDS) and to validate the HbA1c cutoff values of 6.5 and 6.1 % set for the diagnosis of diabetes mellitus by the American Diabetes Association (ADA) and the JDS, respectively. NGSP HbA1c values obtained from the monthly monitoring program of the performance of the NGSP Secondary Reference Laboratories (SRLs) were provided by the NGSP. The samples used in the NGSP monitoring program were also assayed to obtain the JDS values at the Laboratory of Reference Material Institute for Clinical Chemistry Standards (ReCCS) using the KO 500 designated comparison method (DCM) calibrated with a reference material, JDS Lot 4, issued by ReCCS. The results were compared, and the correlation between the two data sets was examined by linear regression. The relationship between the NGSP SRLs values and JDS values for the monitoring program samples was as follows: NGSP = 1.029 × JDS + 0.216. For another sample, JDS Lot 4, the correlation was: NGSP = 1.029 × JDS + 0.187. The two equations are consistent with the cutoff points 6.5 and 6.1 %, used by the ADA and the JDS, respectively.