Comparative evaluation of three different methods for HbA(1c) measurement with High-performance liquid chromatography in diabetic patients

BACKGROUND: The global prevalence of diabetes mellitus is increasing rapidly. Measurement of glycated hemoglobin, predominantly HbA(1c), is fundamental to the management of patients with diabetes. HbA(1c) is used to monitor long-term glycemic control, adjust therapy, assess the quality of diabetes care and predict the risk for the development of complications. While HbA(1c) is the standard method for long-term glycemic control in diabetic patients, there are different methods for measurement of HbA(1c) and all laboratories do not use the reference method (high-performance liquid chromatography [HPLC]). The objective of this study is comparison of three different methods with HPLC to find out which method has an acceptable concordance and correlation with the reference method. MATERIALS AND METHODS: Fifty-eight diabetic patients were assessed in this study. The blood sample of each patient was checked with Diazyme (enzymatic assay), Nycocard (boronate-affinity binding) and Biosystem (micro column chromatography). The values of HbA(1c) of each method were compared with the Knauer-HPLC results. RESULTS: The means of the differential values between each method and HPLC in the ANOVA test are as follows: M = 1.8, SD = 1.09 for Nycocard-HPLC; M = 1.5, SD = 1.08 for biosystem-HPLC; M = 1.3, SD = 1.2 for Diazyme-HPLC. Pearson's correlation coefficient between HPLC and Nycocard; 0.76, HPLC and Diazyme; 0.75 and between HPLC and Biosystem was 0.68. Linear regression parameters for each method with HPLC were also determined. CONCLUSION: Diazyme had a better performance and showed a greater concordance with HPLC among others, although it was not an ideal alternative for HPLC.