A system for non-invasively monitoring a medical condition in a subject via stimulation of a target nerve, the system comprising: a first electrode, wherein the first electrode is configured for placement on a surface of non-glabrous skin, wherein the first electrode is a cathode; a second electrode, wherein the second electrode is configured for placement on a surface of non-glabrous or glabrous skin, wherein the second electrode is an anode; and an electronic control system coupled to the first electrode and the second electrode, wherein the electronic control system is configured to: transcutaneously deliver a first electrical nerve stimulation to the target nerve via the first electrode and the second electrode to determine a baseline current or a baseline voltage for the subject, wherein the baseline current is the current at which a sensory response or a motor response is elicited in the subject as a result of the first electrical nerve stimulation, and wherein the baseline voltage is the voltage at which a sensory response or a motor response is elicited in the subject; and transcutaneously deliver a second electrical nerve stimulation to the target nerve via the first electrode and the second electrode to determine a threshold current or a threshold voltage for the subject, wherein the threshold current is the current at which a sensory response or a motor response is elicited in the subject as a result of the second electrical nerve stimulation, and wherein the threshold voltage is the voltage at which a sensory response or a motor response is elicited in the subject, wherein the medical condition is improved if the threshold current is lower than the baseline current or the threshold voltage is lower than the baseline voltage. a first electrode, wherein the first electrode is configured for placement on a surface of non-glabrous skin, wherein the first electrode is a cathode; a second electrode, wherein the second electrode is configured for placement on a surface of non-glabrous or glabrous skin, wherein the second electrode is an anode; and an electronic control system coupled to the first electrode and the second electrode, wherein the electronic control system is configured to: transcutaneously deliver a first electrical nerve stimulation to the target nerve via the first electrode and the second electrode to determine a baseline current or a baseline voltage for the subject, wherein the baseline current is the current at which a sensory response or a motor response is elicited in the subject as a result of the first electrical nerve stimulation, and wherein the baseline voltage is the voltage at which a sensory response or a motor response is elicited in the subject; and transcutaneously deliver a second electrical nerve stimulation to the target nerve via the first electrode and the second electrode to determine a threshold current or a threshold voltage for the subject, wherein the threshold current is the current at which a sensory response or a motor response is elicited in the subject as a result of the second electrical nerve stimulation, and wherein the threshold voltage is the voltage at which a sensory response or a motor response is elicited in the subject, wherein the medical condition is improved if the threshold current is lower than the baseline current or the threshold voltage is lower than the baseline voltage. transcutaneously deliver a first electrical nerve stimulation to the target nerve via the first electrode and the second electrode to determine a baseline current or a baseline voltage for the subject, wherein the baseline current is the current at which a sensory response or a motor response is elicited in the subject as a result of the first electrical nerve stimulation, and wherein the baseline voltage is the voltage at which a sensory response or a motor response is elicited in the subject; and transcutaneously deliver a second electrical nerve stimulation to the target nerve via the first electrode and the second electrode to determine a threshold current or a threshold voltage for the subject, wherein the threshold current is the current at which a sensory response or a motor response is elicited in the subject as a result of the second electrical nerve stimulation, and wherein the threshold voltage is the voltage at which a sensory response or a motor response is elicited in the subject, wherein the medical condition is improved if the threshold current is lower than the baseline current or the threshold voltage is lower than the baseline voltage.