A method of non-invasively measuring the presence, absence, or concentration of one or more analytes in a tissue of a subject includes exposing at least a portion of a tissue of the subject to electromagnetic radiation; obtaining electromagnetic radiation measurement data of electromagnetic radiation from the tissue; using a mathematical transformation to filter or smooth the electromagnetic radiation measurement data; and determining the presence, absence, or concentration of one or more analytes by determining a radiation signature of the filtered or smoothed electromagnetic radiation measurement data; correlating the radiation signature of the filtered or smoothed electromagnetic radiation measurement data with the presence, absence, or concentration of one or more analytes to determine the presence, absence, or concentration of one or more analytes in the subject.