A system 100, 200 for sensing one or more analytes in a first biofluid and a second biofluid and methods of using said system. The system 100, 200 may include a first subsystem 102, 200a, 200b with a first sensor 120, 122, 220, 222 for sensing a first analyte in the first biofluid and a second subsystem 104, 200b, 200c with a second sensor 124, 126, 222, 224 for sensing a second analyte in the second biofluid. The second analyte may be the same as or different from the first analyte and the second biofluid may be different from the first biofluid. In an embodiment, the first biofluid is a non-sweat biofluid and the second biofluid is sweat. The system 100, 200 may be used to detect lag time for measuring an analyte in one of the biofluids.
