A sensor and an apparatus for non invasive measurement of an analyte concentration the apparatus comprising: a first thermal sensor (106) operable to determine a temperature indicative of a temperature at a location on a skin (122) of a subject an analyte sensor (103) operable to generate a measurement indicative of a concentration of the analyte a heater (109) a controller (216) operable to receive a temperature signal from at least the first thermal sensor and to adjust the heater to maintain a thermal equilibrium at said location on the skin and a processor (213) configured to convert the measurement to a calculated analyte concentration value at a predetermined temperature.
