Correlation of Fasting Plasma Glucose, Hemoglobin Ale and Estimated Average Glucose Levels in Diabetic Patients with Abnormal Hemoglobin in Sirindhorn Hospital

Fasting  plasma glucose  (FPG)  and  hemoglobin  Ale (HbAlc) are  laboratory tests for diabetic  diagnosis  and  monitoring of diabetic control. HbAlc value is also used for  estimating average glucose levels (eAG) in diabetic  patients. However,  HbAlc assay may be unreliable  due to interference by abnormal hemoglobin  or thalassemia. The objectives of this research were to study  the correlation of FPG, HbAlc and eAG in diabetic  patient  with abnormal hemoglobin, and to study  the effect of abnormal hemoglobin  on detection  of HbAlc. In this study,  FPG and HbA lc, which  were  assayed   using  both  ion  exchange HPLC  and  turbidimetric  inhibition immunoassay, showed significantly high  correlation in diabetic patients with abnormal hemoglobin. However, eAG levels calculated from HbAlc values were significantly higher  than FPG levels. Moreover,  HbAlc assay  by ion exchange  HPLC was interfered by HbE. Therefore, this interference should  be concerned for  HbAlc assay  in diabetic  patients with HbE.