Label-free detection of biomarkers has been of significant interest lately which proves to be a powerful means for point-of-care diagnostics. A low-power, low form factor wearable device is proposed for combinatorial detection of glucose in sweat using electrochemical impedance spectroscopy (EIS) technique. The wearable EIS device consists of a sensing analog front end and low-volume ultrasensitive flexible zinc oxide biosensors. Monoclonal antibodies specific to glucose oxidase were immobilized on a thiolated zinc oxide sensing electrode surface resulting in the modulation of charge transfer within the electrical double layer (EDL). The non-faradaic EIS response of the biosensor was used to calibrate the analog front end's response using ratiometric digital Fourier transform (DFT). In this work, thiolated biosensors are dosed with glucose concentrations ranging from 5-200 mg/dL and detection is performed using the analog front end. Continuous dose testing was performed to demonstrate the stability of sensor over prolonged periods of operation for glucose concentrations within the physiologically relevant range reported in synthetic and human sweat buffers. In addition, combinatorial detection of glucose and cortisol is performed to mimic the overall physiological response in hyperglycemic condition reported in the previous literature and demonstrate the reliability of the sensing device.