Since the first demonstration of a biosensor was reported, big efforts have been reported to improve the sensing performance of bioelectronics by investigating the material compositions, device configurations, process optimization, and system integration. In this paper, we demonstrate highly sensitive wearable carbon-based glucose sensors fabricated by all-solution process at low temperature. Solution-processed single-wall carbon nanotube (SWCNT) random networks as a sensing platform were surface-functionalized with the enzyme glucose oxidase (GOD)-nafion composites, which can detect glucose down to 50 mu M with a response time of less than 5 s. We also investigate the sensing mechanism of SWCNT-based glucose sensors through molecular oxidation-reduction reactions in GOD with glucose. Material characterization using X-ray photoelectron spectroscopy and Raman spectra measurements proves the existence of SWCNT random networks with chemical incorporation through a surface-functionalization process. We believe that the proposed wearable SWCNT-based glucose sensors fabricated by all-solution process can open up a promising route to realize a low-cost and high performance health-care diagnosis system integrated with the user's smartphone for diabetic patients.