Lectin-Based Test Estimates Glycated Hemoglobin

The quantitative precipitin method was performed for the interaction between the glucose-specific lectin Concanavalin A (Con A) and the glucose-containing RBC-lysate for the estimation of calculated HbA1c% from a standard curve.

Scientists at the Cancer Centre Welfare Home and Research Institute, (Kolkata, West Bengal, India) selected 16 patients of both sexes with type-2 diabetes, age range 35–60 years, and four patients with newly diagnosed type-1 diabetes, age range 15–41 years . Twenty sex-matched normal healthy subjects, age range 33-65 years, were also included as controls. A precipitation test of red cell lysate and Con-A was performed and the precipitate estimated spectrophotometrically at 480 nm. For reference, plasma glucose was estimated from the diabetic and nondiabetic subjects by glucose oxidase method using phenol 4-aminophenazone and HbA1c% were measured by ion-exchange high performance liquid chromatography (HPLC) method with the Bio-Rad D-10 analyzer (BioRad; Hercules, CA, USA).

The absorbance range of the precipitate was 0.14–0.20 in normal subjects and the corresponding calculated HbA1c% along with plasma glucose levels was 4.1%-5.8% and 82-101 mg/dL, respectively. For the diabetic patients, HbA1c results were between 6.3%-12.2%, and the plasma glucose range was 120-292 mg/dL. Similar results were observed for HbA1c% (6.1%-11.9%) of the same diabetic samples measured by conventional ion-exchange HPLC. The nondiabetic and diabetic hemoglobin variant subjects consisted of HbE-β-thalassemia, β-thalassemia carrier state, HbE trait, and HbS trait, showed similar HbA1c% by the lectin-based assay when compared with standard HPLC method.

The authors concluded that the 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, and moreover, the method is convenient, cheap, and needs no sophisticated instruments, and therefore suitable for laboratories in poor resource settings. The study was published online on January 24, 2012, in the Journal of Clinical Laboratory Analysis.

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