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.
Glucose oxidase is an enzyme that catalyzes the oxidation of beta D- glucose, present in the plasma, to D glucono -1 ,5 - lactone with the formation of hydrogen peroxide. The lactone is then slowly
hydrolysed to D-gluconic acid. The hydrogen peroxide produced is then broken down to oxygen and water by a peroxidase enzyme. Oxygen then reacts with an oxygen acceptor (eg, ortho toluidine) and is converted to a colored compound, which is measured and quantified colorimetrically.