Lectin-based estimation of glycated hemoglobin in diabetes mellitus

This study was undertaken to distinguish between normal and diabetic subjects by lectin-glycated hemoglobin interaction. The quantitative precipitin method was performed for the interaction between glucose-specific lectin Concanavalin A (Con A) and the glucose-containing RBC-lysate for the estimation of calculated HbA1c% from a standard curve. The standard curve was prepared by plotting the optical density of the precipitin for the interaction of standard HbA1c concentration with Con A against HbA1c reference standard. The absorbance range of the precipitate was 0.14-0.20 in normal subjects and the corresponding calculated HbA1c% along with plasma glucose (mg/dl) levels was 4.1-5.8% and 82-101 mg/dl respectively. Higher absorbance values, 0.22-0.42, were obtained in diabetic patients when the calculated HbA1c% was 6.3-12.2% and plasma glucose level was 120-292 mg/dl. Almost similar results were observed for HbA1c% (6.1-11.9%) of the same diabetic samples measured by conventional ion-exchange high performance liquid chromatography (HPLC). Excellent correlation coefficients of the two methods from regression analysis graph for normal (r = 0.98) and diabetic patients (r = 0.99) were observed. Furthermore, nondiabetic and diabetic hemoglobin variant subjects showed similar HbA1c% by our lectin-based assay when compared with standard HPLC method. We conclude that this lectin-based assay may be adopted to estimate glycated hemoglobin level in differentiating between normal and diabetic patients. This assay offers a good correlation with standard HPLC method. Moreover; the method is convenient, cheap, and needs no sophisticated instruments.