Serum, plasma, and whole blood glucose levels are among the most common laboratory assays. Due to self-monitoring of blood glucose (SMBG), blood glucose is also the most common assay performed by patients themselves or their caretakers. Fasting, timed, and casual serum or plasma specimens are run in hospital laboratories for screening, diagnosis, and monitoring of patients.
One of the most common methods to quantify blood glucose levels is the Glucose Oxidase method. Glucose oxidase is an enzyme that catalyzes the oxidation of β-D-glucose, present in the plasma, to D-glucono-1,5-lactone with the formation of hydrogen peroxide. The lactone is then slowly hydrolyzed to D-gluconic acid. The hydrogen peroxide produced is then broken down into oxygen and water by a peroxidase enzyme. Oxygen then reacts with an oxygen acceptor (e.g., ortho toluidine) and is converted to a colored compound, which is measured and quantified colorimetrically.
