Described are inkjet-printed sensors for detecting metabolites in biological samples obtained non-invasively. The sensors may include a backing layer, and at least one set of three electrodes printed from a conducting polymer onto the backing layer. A set of electrodes includes a three-electrode geometry with a reference electrode, a working electrode with a polymeric coating, and a counter electrode. The sensor may be connected to an acquisition system and/or a display system, forming a sensor system. The biological sample may be saliva, sputum, tear, sweat, urine, exudate, blood, plasma, or vaginal discharge. The sensor typically detects metabolites capable of interacting with oxidase or oxido-reductase enzymes. Some of the exemplary metabolites detected by the sensor include glucose, cholesterol, nicotine, carbon monoxide, nitrite, nitrate, alcohol, and bacterial metabolites.