Diaphorase is widely used in biochemical and diagnostic applications due to its ability to catalyze redox reactions involving NADH and NADPH. It plays a key role in enzyme-linked assays, where it acts as a coupling enzyme to regenerate cofactors or amplify detection signals. In clinical diagnostics, diaphorase is employed in glucose and cholesterol test kits to enhance sensitivity and accuracy by facilitating the reduction of tetrazolium salts into colored formazan products, enabling easy colorimetric detection. It is also utilized in biosensors for real-time monitoring of metabolites, leveraging its specificity and stability under various assay conditions. Additionally, diaphorase finds application in research settings for studying electron transfer mechanisms and in the development of biofuel cells, where it contributes to efficient energy conversion through NADH oxidation.