Devices and methods are provided for determining concentration of at least one analyte in a body fluid sample such as blood, especially a blood glucose concentration. In the methods, a test element is provided that has at least one reagent element configured so as to carry out at least one optically detectable detection reaction in the presence of the analyte. The body fluid sample is applied to the test element and a time course of at least one optical measurement variable of the reagent element is detected. At least one first time interval of the time course of the optical measurement variable is used to determine at least one disturbance variable value in the body fluid sample, in particular a concentration of a disturbance variable such as hematocrit. At least one second time interval of the time course is used to determine analyte concentration. The at least one disturbance variable value can be used to correct/compensate the analyte concentration.