Abstract: One embodiment of the invention is a method for obtaining an estimate of an analyte concentration in a first fluid. First, measurements of an analyte concentration in a second fluid are obtained using a sensing device. An analyte concentration estimate in the first fluid is determined from these measurements by minimizing the relation: f[b]=x2[b]+&lgr;&PSgr;[b], where b is a vector representing analyte concentration in the first body fluid, X2[b] is a function representing a fit between the estimates and the measurements, &lgr; is a weighting function, and &PSgr;[b] is a function indicating smoothness of the analyte concentration estimates in the first fluid. Another embodiment includes a sensing device for obtaining the measurements of an analyte concentration in the first fluid and a processor configured and arranged to determine the analyte concentration in the first body fluid according to this method.

Abstract: A method for obtaining an estimate of an analyte concentration in a first fluid from an analyte concentration in a second fluid is disclosed. The method includes obtaining measurements of an analyte concentration in a second fluid by using a sensing device. The analyte concentration estimate in the first fluid is determined from these measurements. Also disclosed is a sensing device for obtaining the measurements of an analyte concentration in the first fluid and a processor configured and arranged to determine the analyte concentration in the first body fluid according to this method. This method and device can be used, for example, to determine blood glucose concentration from measurements of the glucose concentration in subcutaneous tissue. These measurements may be made using in vitro or in vivo samples. In some instances, a subcutaneously implanted sensing device, such as electrochemical sensor, is used to make the measurements.