A glucose sensor comprising: an adhesive layer adapted to bond to skin of an individual, wherein the adhesive layer comprises an opening adapted to allow sweat to migrate from the skin of the individual to a glucose sensing complex within the glucose sensor; a substrate layer disposed over the adhesive layer and comprising a glucose sensing complex, wherein substrate layer comprises hydrophilic regions and hydrophobic regions adapted to modulate the flow of sweat through the glucose sensor so as to accumulate sweat that migrates from the skin of the individual in to the sensor, and the glucose sensing complex comprises: an enzyme complex that reacts with glucose and comprises: glucose oxidase, glucose dehydrogenase or a hexokinase/glucose-6-phosphate complex; wherein the glucose sensing complex is adapted to measure glucose in volumes of sweat that are between 5 microliters and 25 microliters; a colorimetric indicator that changes color following reaction of glucose with the enzyme complex; a spacer layer disposed over the substrate layer, wherein the spacer layer comprises a port that allows visualization of the glucose sensing complex in the substrate layer; and a cover layer disposed over the spacer layer, wherein the cover layer comprises a port that allows visualization of the glucose sensing complex in substrate layer, wherein a region of the substrate layer in which the glucose sensing complex is disposed comprises preloaded buffering compounds adapted to modulate the pH at which the glucose sensing complex senses glucose. an adhesive layer adapted to bond to skin of an individual, wherein the adhesive layer comprises an opening adapted to allow sweat to migrate from the skin of the individual to a glucose sensing complex within the glucose sensor; a substrate layer disposed over the adhesive layer and comprising a glucose sensing complex, wherein substrate layer comprises hydrophilic regions and hydrophobic regions adapted to modulate the flow of sweat through the glucose sensor so as to accumulate sweat that migrates from the skin of the individual in to the sensor, and the glucose sensing complex comprises: an enzyme complex that reacts with glucose and comprises: glucose oxidase, glucose dehydrogenase or a hexokinase/glucose-6-phosphate complex; wherein the glucose sensing complex is adapted to measure glucose in volumes of sweat that are between 5 microliters and 25 microliters; a colorimetric indicator that changes color following reaction of glucose with the enzyme complex; an enzyme complex that reacts with glucose and comprises: glucose oxidase, glucose dehydrogenase or a hexokinase/glucose-6-phosphate complex; wherein the glucose sensing complex is adapted to measure glucose in volumes of sweat that are between 5 microliters and 25 microliters; a colorimetric indicator that changes color following reaction of glucose with the enzyme complex; a spacer layer disposed over the substrate layer, wherein the spacer layer comprises a port that allows visualization of the glucose sensing complex in the substrate layer; and a cover layer disposed over the spacer layer, wherein the cover layer comprises a port that allows visualization of the glucose sensing complex in substrate layer, wherein a region of the substrate layer in which the glucose sensing complex is disposed comprises preloaded buffering compounds adapted to modulate the pH at which the glucose sensing complex senses glucose. <EOS>