A flexible, body-mountable analyte sensing device includes a flexible substrate configured for mounting to skin of a living body. The sensing device additionally includes a sensor probe attached to the flexible substrate and configured to penetrate the skin such that a sensor disposed on the end of the sensor probe can be exposed to an analyte in interstitial fluid. The sensor could be an electrochemical sensor that includes two or more electrodes disposed at the end of the sensor probe and configured to electrochemically detect the analyte. The sensing device is configured to display detected concentrations or other information about the analyte in the interstitial fluid. The flexible substrate of the sensing device is configured to be adhered or otherwise mounted to the skin in a manner that minimally impacts activities of the living body.