A method and apparatus for noninvasively measuring the concentration of a target analyte in a sample matrix using a fiberless transflectance probe is described. It includes directing a beam of electromagnetic radiation, consisting of at least two components of different wavelengths, to the sample matrix and conducting the backscattered radiation to a detector which outputs a signal indicative of the differential absorption of the two wavelengths in the sample matrix. The transflectance probe comprises a tapered tubular housing having an inner reflective surface, an optical rod having an outer reflective surface, and a detection window which serves as an interface between the probe and the surface of the sample matrix. The method and apparatus described are particularly useful in measuring the concentration of glucose in tissue containing blood.
