To measure the glucose concentration in blood is an important target for point-of-care diagnostics. We integrated a colorimetric assay on synthetic paper, a novel lateral flow test substrate, for quantitative glucose measurement. At first, we dropped a colorimetric enzyme assay in silk solution on one end of the synthetic paper test strip and dried it in a vacuum chamber for overnight. After that, we flowed glucose solution on the test strip, imaged the test strip by smartphone, and analyzed the images with ImageJ. Exponential fitting of the experimental data revealed a low limit of detection of the assay to be 0.21 mM, and the R-2 is 0.99 for the concentration (0 - 15 mM), which covers the clinically relevant blood glucose concentration (2 - 12 mM). This test strip can he further developed into a test for glucose quantification in whole blood.