1. A method for estimating a glucose level of a person having diabetes, the method comprising: receiving into a computing device a plurality of measured glucose results from a glucose sensor coupled to the person; using the computing device to analyze the plurality of measured glucose results with a probability analysis tool configured to determine a probability of glucose sensor accuracy P A based on the plurality of measured glucose results; and using the computing device to estimate the glucose level of the person with a recursive filter configured to estimate the glucose level based on the plurality of measured glucose results weighted with the probability of glucose sensor accuracy P A .