The present commercialized portable glucose meters work with single-use zymochemistry test strips, the signal testing principle of which includes electrochemistry and optics method. The technology of blood ingredients separating filtration membrane is applied above the enzyme reaction layer, which actually tests the plasma. Upon design and calibration, the factories may report the result according to the actual tested plasma concentration; they may calculate the final concentration based on the whole blood sample volume; or they may transform the tested signal into whole blood concentration according to average hematocrit, the latter of which is whole blood glucose value.  Most of the early glucose instruments measure whole blood glucose; however, more contemporary instruments are primarily those that measure plasma glucose.