A method of measuring the concentration of an analyte in a physiological fluid sample, the method comprising the steps of: (a) providing a test device comprising a test fluid application portion having at least a pair of electrodes and a reagent; (b) providing a predetermined potential across the at least a pair of electrodes; (c) measuring a current at the at least a pair of electrodes; and (d) initiating a first predetermined time period T 1 and a second predetermined time period T ESD; (e) determining a maximum peak value time T p; and either if the magnitude of the current remains above a threshold current value for the time period T ESD, measuring two current readings at the at least a pair of electrodes after the maximum peak value time T p and during the time period T 1, and using the magnitude of the current at the end of the time period T 1 as a test reading indicative of the concentration of an analyte in a physiological fluid present in the test fluid application area of the test device if the difference between the two current readings taken during the time period T 1 is less than an error threshold or outputting an error message if the difference between the two current readings taken during the time period T 1 is greater than an error threshold; or if the magnitude of the current falls below the threshold current value for the time period T ESD, returning to step (c); wherein the time period T ESD comprises an initial portion of the time period T 1 and commences at the same time as T 1; and wherein the time period T ESD is sufficiently long to detect a fall in current below the threshold current value in the event of electrostatic discharge; and wherein a difference in current values above the error threshold is indicative of a system defect or user error. (a) providing a test device comprising a test fluid application portion having at least a pair of electrodes and a reagent; (b) providing a predetermined potential across the at least a pair of electrodes; (c) measuring a current at the at least a pair of electrodes; and (d) initiating a first predetermined time period T 1 and a second predetermined time period T ESD; (e) determining a maximum peak value time T p; and either if the magnitude of the current remains above a threshold current value for the time period T ESD, measuring two current readings at the at least a pair of electrodes after the maximum peak value time T p and during the time period T 1, and using the magnitude of the current at the end of the time period T 1 as a test reading indicative of the concentration of an analyte in a physiological fluid present in the test fluid application area of the test device if the difference between the two current readings taken during the time period T 1 is less than an error threshold or outputting an error message if the difference between the two current readings taken during the time period T 1 is greater than an error threshold; or if the magnitude of the current falls below the threshold current value for the time period T ESD, returning to step (c); wherein the time period T ESD comprises an initial portion of the time period T 1 and commences at the same time as T 1; and wherein the time period T ESD is sufficiently long to detect a fall in current below the threshold current value in the event of electrostatic discharge; and wherein a difference in current values above the error threshold is indicative of a system defect or user error. if the magnitude of the current remains above a threshold current value for the time period T ESD, measuring two current readings at the at least a pair of electrodes after the maximum peak value time T p and during the time period T 1, and using the magnitude of the current at the end of the time period T 1 as a test reading indicative of the concentration of an analyte in a physiological fluid present in the test fluid application area of the test device if the difference between the two current readings taken during the time period T 1 is less than an error threshold or outputting an error message if the difference between the two current readings taken during the time period T 1 is greater than an error threshold; or if the magnitude of the current falls below the threshold current value for the time period T ESD, returning to step (c); wherein the time period T ESD comprises an initial portion of the time period T 1 and commences at the same time as T 1; and wherein the time period T ESD is sufficiently long to detect a fall in current below the threshold current value in the event of electrostatic discharge; and wherein a difference in current values above the error threshold is indicative of a system defect or user error.