Adherent cells cultured on microcarrier beads were packed into a renewable microcolumn within Lab-on-valve system. Glucose assay is performed through the use of a two-step, NAD-linked enzymatic process. The course of the assay is monitored in real time, by absorbance of NADH at 340 nm. The flow cell is based on a novel plug/nozzle design. The assay has a linear dynamic range for glucose of 0.1 to 5.6 mM. The design of the (µSI-LOV) system allows the measurement to be carried out using only 40 μL of the enzyme reagent and 3 μL of interrogated cell/bead sample. The technique was tested on a murine hepatocyte cell line (TABX2S) adhered to Cytopore beads. Rapid cellular glucose consumption, in this technique, is facilitated by a high cell density, which allows a large number of cells (104–105) held in a very small volume of the bioreactor.