Enzymatic electrochemical method for quantification of analytes in isolated biological fluid samples that comprises the following stages: a) introduce said sample in an electrochemical system formed by at least a biosensor strip A comprising at least: - a working electrode modified with at least an enzyme and an electrochemical mediator, - a reference electrode and - an auxiliary electrode or counter-electrode and at least a biosensor strip B comprising at least: - a working electrode modified with the same enzyme and the same electrochemical mediator as strip A and additionally at least a cofactor, - a reference electrode and - an auxiliary electrode or counter-electrode; b) apply a constant potential to the biosensor strips A and B during a set period of time; c) measure the current intensity on each of the biosensors strips, wherein at biosensor strip B the current intensity is produced by the re-oxidation of the cofactor on the working electrode, facilitated by the mediator, after having been initially reduced due to the reaction between the enzyme and the analyte, and subtract the response obtained in each of the electrodes of the strip A from the response obtained in each of the homologous electrode of the strip B; d) translate the substracted current intensity data obtained in stage (c) to analyte concentration by means of a calibration curve obtained from samples of a synthetic biological fluid comprising different concentrations of the analyte to be determined. a) introduce said sample in an electrochemical system formed by at least a biosensor strip A comprising at least: - a working electrode modified with at least an enzyme and an electrochemical mediator, - a reference electrode and - an auxiliary electrode or counter-electrode and at least a biosensor strip B comprising at least: - a working electrode modified with the same enzyme and the same electrochemical mediator as strip A and additionally at least a cofactor, - a reference electrode and - an auxiliary electrode or counter-electrode; - a working electrode modified with at least an enzyme and an electrochemical mediator, - a reference electrode and - an auxiliary electrode or counter-electrode - a working electrode modified with the same enzyme and the same electrochemical mediator as strip A and additionally at least a cofactor, - a reference electrode and - an auxiliary electrode or counter-electrode; b) apply a constant potential to the biosensor strips A and B during a set period of time; c) measure the current intensity on each of the biosensors strips, wherein at biosensor strip B the current intensity is produced by the re-oxidation of the cofactor on the working electrode, facilitated by the mediator, after having been initially reduced due to the reaction between the enzyme and the analyte, and subtract the response obtained in each of the electrodes of the strip A from the response obtained in each of the homologous electrode of the strip B; d) translate the substracted current intensity data obtained in stage (c) to analyte concentration by means of a calibration curve obtained from samples of a synthetic biological fluid comprising different concentrations of the analyte to be determined.