A method and apparatus for measuring a blood analyte concentration using an inexpensive, low precision sensor device is provided. One embodiment of the method includes obtaining energy absorption measurement data through a body part of an individual. A plurality of indicator variables are subsequently calculated from the energy absorption measurement data. An indicator variable from the plurality of indicator variables having the highest correlation to blood glucose level is determined, and a first optical term based on the indicator variable with the highest correlation to blood glucose level is allocated to form a regression analysis equation. An estimated value of the blood analyte concentration using the regression analysis equation is calculated.