Absorption spectroscopy for the estimation of glycated hemoglobin (HbA1c) for the diagnosis and management of diabetes mellitus: A pilot study

Objective: The purpose of this study was to explore the possibility of using absorption spectroscopy technique for the estimation of glycated hemoglobin HbA1c (%)_. Background data: Glycated hemoglobin (HbA1c) is an important marker in the diagnosis and management of diabetes mellitus. Different assay techniques have been employed for the estimation of glycated hemoglobin, including ion exchange high performance liquid chromatography (HPLC), electrophoresis, affinity chromatography, immunoturbidimetric assay and colorimetric assays, which measure different glycated products and report using different units. Spectroscopic measurements have been shown to be very sensitive and nondestructive, and require very little quantity of material for analysis. In the present study, we have employed absorption spectroscopy technique for the estimation of glycated hemoglobin in hemolysate samples of diabetic patients. Materials and methods: The blood samples of individuals with normal glycemic status and confirmed diabetic patients were collected from the Clinical Biochemistry Laboratory, Kasturba Hospital, Manipal. The absorption spectra of glycated hemoglobin (HbA1c) samples were recorded in the spectral range 200-850 nm using an optic fiber based Ocean Optics CHEMUSB4-UV-VIS single beam spectrophotometer. The parameter "area under the curve" of each baseline corrected absorption spectrum was used for the estimation of HbA1c (%). The glycated hemoglobin values obtained by this spectroscopic method were compared with the values reported by the standard ion exchange HPLC method. Results: A total of 30 absorption spectra were recorded from hemolysate samples with HbA1c (%) in the range 4-10.5%. A good correlation was observed between the glycated hemoglobin values obtained by the spectroscopic method and those obtained by the standard HPLC method. Conclusions: It appears that the direct absorption spectroscopy of hemolysate samples, therefore, may be utilized as a supplementary technique for the estimation of HbA1c (%), even at the primary healthcare centers.