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Disclosed herein are systems and methods for calibrating a continuous analyte sensor, such as a continuous glucose sensor. One such system utilizes one or more electrodes to measure an additional analyte. Such measurements may provide a baseline or sensitivity measurement for use in calibrating the

Disclosed herein are systems and methods for calibrating a continuous analyte sensor, such as a continuous glucose sensor. One such system utilizes one or more electrodes to measure an additional analyte. Such measurements may provide a baseline or sensitivity measurement for use in calibrating the sensor. Furthermore, baseline and/or sensitivity measurements may be used to trigger events such as digital filtering of data or suspending display of data.

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What is claimed is: 1. A method for processing data from a glucose sensor in a host, the method comprising: measuring a first signal associated with glucose and non-glucose related electroactive compounds, wherein the first signal is measured at a first electrode disposed beneath an active enzymati

What is claimed is: 1. A method for processing data from a glucose sensor in a host, the method comprising: measuring a first signal associated with glucose and non-glucose related electroactive compounds, wherein the first signal is measured at a first electrode disposed beneath an active enzymatic portion of a membrane system; measuring a second signal associated with at least one non-glucose related electroactive compound, wherein the second signal is measured at a second electrode disposed beneath a non-enzymatic portion of the membrane system; and calculating, in an electronic device, a change in the second signal over a time period. 2. The method of claim 1, further comprising subtracting the second signal from the first signal, whereby a differential signal comprising at least one glucose sensor data point is determined. 3. The method of claim 2, wherein subtracting the second signal from the first signal is performed electronically in the sensor. 4. The method of claim 2, wherein subtracting the second signal from the first signal is performed digitally in the sensor, an associated receiver, or combinations thereof. 5. The method of claim 2, further comprising calibrating the glucose sensor, which comprises: receiving reference data comprising at least one reference data point; providing at least one matched data pair by matching the reference data to substantially time corresponding sensor data; and calibrating the glucose sensor using the at least one matched data pair and the differential signal. 6. The method of claim 2, further comprising filtering the at least one glucose sensor data point when the change in the second signal rises above a threshold during the time period. 7. The method of claim 1, further comprising calibrating the glucose sensor in response to the change in the second signal over the time period. 8. The method of claim 7, wherein calibrating the glucose sensor comprises receiving reference data comprising at least one reference data point. 9. The method of claim 7, wherein calibrating the glucose sensor is performed repeatedly at a frequency, based at least in part on the change in the second signal over the time period. 10. The method of claim 1, wherein calibrating the glucose sensor is based at least in part on the change in the second signal over the time period. 11. The method of claim 1, further comprising prohibiting calibration of the glucose sensor when the change in the second signal rises above a threshold during the time period. 12. The method of claim 1, further comprising measuring a third signal in the host by obtaining at least one non-glucose constant data point, wherein the third signal is measured beneath the membrane system. 13. The method of claim 12, further comprising monitoring the third signal over the time period, whereby a sensitivity change associated with solute transport through the membrane system is measured. 14. The method of claim 13, further comprising calibrating the glucose sensor in response to the sensitivity change measured over the time period. 15. The method of claim 14, wherein calibrating the glucose sensor comprises receiving reference data comprising at least one reference data point. 16. The method of claim 14, wherein calibrating the glucose sensor is based at least in part on the sensitivity change. 17. The method of claim 14, wherein calibrating the glucose sensor is performed repeatedly at a frequency, based at least in part on the sensitivity change. 18. The method of claim 13, further comprising determining glucose transport stability through the membrane system, wherein the glucose transport stability corresponds to the sensitivity change over the period of time. 19. The method of claim 18, further comprising prohibiting calibration of the glucose sensor when the glucose transport stability falls below a threshold. 20. The method of claim 18, further comprising filtering a glucose-related sensor data point when the glucose transport stability falls below a threshold. 21. The method of claim 12, wherein an oxygen-measuring electrode disposed beneath the non-enzymatic portion of the membrane system measures the third signal. 22. The method of claim 12, wherein the first electrode measures the third signal by incrementally measuring oxygen. 23. The method of claim 12, wherein an oxygen sensor disposed beneath the membrane system measures the third signal. 24. The method of claim 12, wherein a urea-measuring electrode disposed beneath the non-enzymatic portion of the membrane system measures the third signal. 25. The method of claim 12, wherein the first electrode measures the third signal by incrementally measuring urea. 26. The method of claim 12, wherein a urea sensor disposed beneath the membrane system measures the third signal. 27. The method of claim 1, further comprising determining whether a glucose-to-oxygen ratio exceeds a threshold level by calculating a value from the first signal and the second signal, wherein the value is indicative of the glucose-to-oxygen ratio. 28. The method of claim 1, further comprising measuring a change in the sensitivity of at least one of the first electrode or the second electrode. 29. The method of claim 28, further comprising calibrating the glucose-related sensor data point in response to a change in the sensitivity meeting one or more criteria. 30. A system for measuring glucose in a host, the system comprising: a first working electrode configured to generate a first signal associated with glucose related and non-glucose related electroactive compounds, wherein the first electrode is disposed beneath an active enzymatic portion of a membrane system on a glucose sensor; a second working electrode configured to generate a second signal associated with at least one non-glucose related electroactive compound, wherein the second electrode is disposed beneath a non-enzymatic portion of the membrane system on the glucose sensor; and a processor module configured to calculating a change in the measure a change in the second signal over a time period. 31. The system of claim 30, further comprising a subtraction module configured to subtract the second signal from the first signal, whereby a differential signal comprising at least one glucose sensor data point is determined. 32. The system of claim 31, wherein the subtraction module comprises a differential amplifier configured to electronically subtract the second signal from the first signal. 33. The system of claim 31, wherein the subtraction module comprises at least one of hardware or software, configured to digitally subtract the second signal from the first signal. 34. The system of claim 31, further comprising a reference input module adapted to obtain reference data comprising at least one reference data point, wherein the processor module is configured to format at least one matched data pair by matching the reference data to substantially time corresponding glucose sensor data and subsequently calibrating the system using at least one matched data pair and the differential signal. 35. The system of claim 31, wherein the processor module is configured to filter the glucose sensor data point when the change in the second signal rises above a threshold during the time period. 36. The system of claim 30, further comprising a reference electrode, wherein the first working electrode and the second working electrode are operatively associated with the reference electrode. 37. The system of claim 36, further comprising a counter electrode, wherein the first working electrode and the second working electrode are operatively associated with the counter electrode. 38. The system of claim 30, further comprising a first reference electrode and a second reference electrode, wherein the first reference electrode is operatively associated with the first working electrode, and wherein the second reference electrode is operatively associated with the second working electrode. 39. The system of claim 38, further comprising a first counter electrode and a second counter electrode, wherein the first counter electrode is operatively associated with the first working electrode, and wherein the second counter electrode is operatively associated with the second working electrode. 40. The system of claim 30, wherein the processor module is configured to calibrate the system in response to the change in the second signal over the time period. 41. The system of claim 40, wherein the processor module is configured to request reference data comprising at least one reference data point, wherein the processor module is configured to recalibrate the system using the reference data. 42. The system of claim 30, wherein the processor module is configured to calibrate the system based at least in part on the change in the second signal measured over the time period. 43. The system of claim 30, wherein the processor module is configured to repeatedly recalibrate at a frequency, based at least in part on the change in the second signal over the time period. 44. The system of claim 30, wherein the processor module is configured to prohibit calibration of the system when the change in the second signal rises above a threshold during the time period. 45. The system of claim 30, further comprising a third electrode configured to generate a third signal, the third signal comprising at least one non-glucose constant analyte data point, wherein the third electrode is disposed beneath the membrane system on the sensor. 46. The system of claim 45, wherein the third electrode is configured to measure oxygen. 47. The system of claim 45, wherein the processor module is configured to monitor the third signal over the time period, whereby a sensitivity change associated with solute transport through the membrane system is measured. 48. The system of claim 47, wherein the processor module is configured to calibrate the glucose-related sensor data point in response to the sensitivity change. 49. The system of claim 47, wherein the processor module is configured to calibrate the glucose-related sensor data point repeatedly at a frequency, based at least in part on the sensitivity change. 50. The system of claim 49, wherein the processor module is configured to prohibit calibration of the glucose-related sensor data point when the stability of glucose transport falls below a threshold. 51. The system of claim 49, wherein the processor module is configured to filter a glucose-related sensor data point when the stability of glucose transport falls below a threshold. 52. The system of claim 45, wherein the processor module is configured to receive reference data comprising at least one reference data point, wherein the processor module is configured to calibrate the glucose sensor data point using the reference data point. 53. The system of claim 47, further comprising a stability module configured to determine a stability of glucose transport through the membrane system, wherein the stability of glucose transport is correlated with the sensitivity change. 54. The system of claim 45, wherein the third electrode is configured to measure urea. 55. The system of claim 30, wherein the processor module is configured to determine whether a glucose-to-oxygen ratio exceeds a threshold level, wherein a value indicative of the glucose-to-oxygen ratio is calculated from the first signal and the second signal. 56. The system of claim 30, wherein the processor module is configured to determine a change in the sensitivity of at least one of the first working electrode or the second working electrode. 57. The system of claim 56, wherein the processor module is configured to calibrate a glucose-related sensor data point in response to a sensitivity change meeting one or more criteria.