A test sensor for determining an analyte concentration in a fluid sample, comprising: a fluid-receiving area for receiving a fluid sample, the fluid-receiving area containing a reagent that produces a measurable reaction with an analyte in the sample, the test sensor having a test-sensor temperature and the reagent having a reagent temperature, the test sensor being configured to be received in the opening of a meter, the meter being configured to determine a measurement of the reaction between the reagent and the analyte; and a temperature-dependent element disposed along a surface of the test sensor, characterized in that the temperature-dependent element includes a grating (130C,130D), the grating (130C,130D), including a series of parallel linear structures equally separated by a distance that changes in response to temperature, and the temperature-dependent element is disposed along the surface of the test sensor so that the temperature-dependent element can be detected inside the meter when the test sensor is received into the opening, the meter including a temperature-measuring system configured to determine a measurement of the test-sensor temperature from the temperature-dependent element when the temperature-dependent element is inside the meter, the temperature-measuring system (250C, 250D) including a light source (252C, 252D) and light detector (254C, 254D), the grating being configured to receive incident light directed from the light source, the light detector (254C, 254D) being configured to receive, from the grating (130C, 130D) disposed inside the meter, diffracted light that changes according to changes in the distance separating the linear structures of the grating, the temperature-measuring system (250C, 250D) determining the measurement of the test-sensor temperature according to the diffracted light, the meter being configured to determine a concentration of the analyte in the sample using the measurement of the reaction and the measurement of the test-sensor temperature. a fluid-receiving area for receiving a fluid sample, the fluid-receiving area containing a reagent that produces a measurable reaction with an analyte in the sample, the test sensor having a test-sensor temperature and the reagent having a reagent temperature, the test sensor being configured to be received in the opening of a meter, the meter being configured to determine a measurement of the reaction between the reagent and the analyte; and a temperature-dependent element disposed along a surface of the test sensor, characterized in that the temperature-dependent element includes a grating (130C,130D), the grating (130C,130D), including a series of parallel linear structures equally separated by a distance that changes in response to temperature, and the temperature-dependent element is disposed along the surface of the test sensor so that the temperature-dependent element can be detected inside the meter when the test sensor is received into the opening, the meter including a temperature-measuring system configured to determine a measurement of the test-sensor temperature from the temperature-dependent element when the temperature-dependent element is inside the meter, the temperature-measuring system (250C, 250D) including a light source (252C, 252D) and light detector (254C, 254D), the grating being configured to receive incident light directed from the light source, the light detector (254C, 254D) being configured to receive, from the grating (130C, 130D) disposed inside the meter, diffracted light that changes according to changes in the distance separating the linear structures of the grating, the temperature-measuring system (250C, 250D) determining the measurement of the test-sensor temperature according to the diffracted light, the meter being configured to determine a concentration of the analyte in the sample using the measurement of the reaction and the measurement of the test-sensor temperature.