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Systems and methods for processing sensor analyte data, including initiating calibration, updating calibration, evaluating clinical acceptability of reference and sensor analyte data, and evaluating the quality of sensor calibration. During initial calibration, the analyte sensor data is evaluated o

Systems and methods for processing sensor analyte data, including initiating calibration, updating calibration, evaluating clinical acceptability of reference and sensor analyte data, and evaluating the quality of sensor calibration. During initial calibration, the analyte sensor data is evaluated over a period of time to determine stability of the sensor. The sensor may be calibrated using a calibration set of one or more matched sensor and reference analyte data pairs. The calibration may be updated after evaluating the calibration set for best calibration based on inclusion criteria with newly received reference analyte data. Fail-safe mechanisms are provided based on clinical acceptability of reference and analyte data and quality of sensor calibration. Algorithms provide for optimized prospective and retrospective analysis of estimated blood analyte data from an analyte sensor.

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What is claimed is: 1. A method for calibrating a substantially continuous analyte sensor, the method comprising: receiving a data stream from an analyte sensor, including one or more sensor data points; receiving reference data from a reference analyte monitor, comprising one or more reference dat

What is claimed is: 1. A method for calibrating a substantially continuous analyte sensor, the method comprising: receiving a data stream from an analyte sensor, including one or more sensor data points; receiving reference data from a reference analyte monitor, comprising one or more reference data points; providing at least one matched data pair by matching reference analyte data to substantially time corresponding sensor data; creating a conversion function based on said at least one matched data pair; evaluating said at least one matched data pair, including at least one of 1) ensuring said at least one matched data pair is within a predetermined time range, 2) ensuring said at least one matched data pair is no older than a predetermined value, 3) ensuring said at least one matched data pair is substantially distributed with additional matched data pairs, if present, between high and low matched data pairs over a predetermined time range, and 4) ensuring said at least one matched data pair is within a predetermined range of analyte values, wherein the step of evaluating said at least one matched data pair further comprises at least one of evaluating a rate of change of the analyte concentration, evaluating a congruence of respective sensor and reference data in a matched data pair, and evaluating physiological changes; and subsequently modifying said conversion function if such modification is required by said evaluation. 2. The method of claim 1, wherein the step of evaluating comprises evaluating an initial matched data pair. 3. The method of claim 1, wherein the step of evaluating comprises evaluating at least one subsequently received matched data pair. 4. The method of claim 1, wherein the step of evaluating comprises evaluating a plurality of matched data pairs. 5. The method of claim 1, wherein the step of receiving sensor data comprises receiving a data stream from an implantable analyte sensor. 6. The method of claim 1, wherein the step of receiving sensor data comprises receiving a data stream that has been algorithmically smoothed. 7. The method of claim 1, wherein the step of receiving sensor data stream comprises algorithmically smoothing said data stream. 8. The method of claim 1, wherein the step of receiving reference data comprises downloading reference data via a wireless connection. 9. The method of claim 1, wherein the step of receiving reference data comprises downloading reference data via a wireless connection. 10. The method of claim 1, wherein the step of receiving reference data from a reference analyte monitor comprises receiving within a receiver internal communication from a reference analyte monitor integral with said receiver. 11. The method of claim 1, wherein the reference analyte monitor comprises self-monitoring of blood analyte. 12. The method of claim 1, wherein the step of creating a conversion function comprises linear regression. 13. The method of claim 1, wherein the step of creating a conversion function comprises non-linear regression. 14. The method of claim 1, wherein the step of creating a conversion function is based on between one matched data pair and six matched data pairs. 15. The method of claim 1, wherein the step of creating a conversion function is based on at least two matched data pairs. 16. A method for calibrating a substantially continuous analyte sensor, the method comprising: receiving a data stream from an analyte sensor, including one or more sensor data points; receiving reference data from a reference analyte monitor, comprising one or more reference data points; providing at least one matched data pair by matching reference analyte data to substantially time corresponding sensor data; forming a calibration set including said at least one matching data pair; creating a conversion function based on said calibration set; converting sensor data into calibrated data using said conversion function; subsequently obtaining one or more additional reference data points and creating one or more new matched data pair; evaluating said calibration set when said new matched data pair is created, wherein evaluating said calibration set includes at least one of 1) ensuring matched data pair in said calibration set span a predetermined time range, 2) ensuring matched data pair in said calibration set are no older than a predetermined value, 3) ensuring said calibration set has substantially distributed high and low matched data pair over said predetermined time range, and 4) allowing matched data pair only within a predetermined range of analyte values; and subsequently modifying said calibration set if such modification is required by said evaluation, wherein the step of forming a calibration set further comprises determining a value for n, where n is greater than one and represents the number of matched data pair in the calibration set, wherein the step of determining a value for n is determined as a function of the frequency of the received reference data points and signal strength over time. 17. The method of claim 1, further comprising determining a set of matched data pairs responsive to the evaluating step. 18. The method of claim 17, further comprising repeating the step of creating said conversion function using said set of matched data pairs. 19. The method of claim 1 or 18, further comprising converting sensor data into calibrated data using said conversion function. 20. A system for calibrating a substantially continuous analyte sensor, the system comprising: means for receiving a data stream from an analyte sensor, a plurality of time-spaced sensor data points; means for receiving reference data from a reference analyte monitor, comprising one or more reference data points; means for providing one or more matched data pairs by matching reference analyte data to substantially time corresponding sensor data; means for creating a conversion function based on said one or more matched data pairs; means for evaluating said one or more matched data pairs including at least one of 1) ensuring one or more matched data pairs is within a predetermined time range, 2) ensuring one or more matched data pairs are no older than a predetermined value, 3) ensuring said one or more matched data pairs have substantially distributed high and low matched data pairs over a predetermined time range, and 4) ensuring said one or more matched data pairs are within a predetermined range of analyte values, wherein said means for evaluating said one or more matched data pairs further comprises at least one means for evaluating a rate of change of the analyte concentration, means for evaluating a congruence of respective sensor and reference data in matched data pairs, and means for evaluating physiological changes; and means for modifying said conversion function if such modification is required by said means for evaluating. 21. The system of claim 20, wherein said means for evaluating comprises means for evaluating one or more initial matched data pairs. 22. The system of claim 20, wherein said means for evaluating comprises means for evaluating one or more subsequently received matched data pairs. 23. The system of claim 20, wherein said means for evaluating comprises means for evaluating a plurality of matched data pairs. 24. The system of claim 20, wherein said means for receiving sensor data comprises means for receiving sensor data from an implantable analyte sensor. 25. The system of claim 20, wherein said means for receiving sensor data comprises means for receiving sensor data that has been algorithmically smoothed. 26. The system of claim 20, wherein said means for receiving sensor data comprises means for algorithmically smoothing said receiving sensor data. 27. The system of claim 20, wherein said means for receiving reference data comprises means for downloading reference data via a cabled connection. 28. The system of claim 20, wherein said means for receiving reference data comprises means for downloading reference data via a wireless connection. 29. The system of claim 20, wherein said means for receiving reference data from a reference analyte monitor comprises means for receiving within a receiver internal communication from a reference analyte monitor integral with said receiver. 30. The system of claim 20, wherein said means for receiving reference data comprises means for receiving from a self monitoring of blood analyte. 31. The system of claim 20, wherein said means for creating a conversion function comprises means for performing linear regression. 32. The system of claim 20, wherein said means for creating a conversion function comprises means for performing non-linear regression. 33. The system of claim 20, wherein said means for creating a conversion function is based on between one matched data pair and six matched data pairs. 34. The system of claim 23, wherein said means for creating a conversion function is based on at least two matched data pairs. 35. A system for calibrating a substantially continuous analyte sensor, the system comprising: means for receiving a data stream from an analyte sensor, a plurality of time-spaced sensor data points; means for receiving reference data from a reference analyte monitor, comprising one or more reference data points; means for providing one or more matched data pair by matching reference analyte data to substantially time corresponding sensor data; means for forming a calibration set comprising at least one matched data pair; means for creating a conversion function based on said calibration set; means for converting sensor data into calibrated data using said conversion function; subsequently obtaining one or more additional reference data points and creating one or more new matched data pair; means for evaluating said calibration set when said new matched data pair is created, wherein evaluating said calibration set includes at least one of 1) ensuring matched data pair in said calibration set span a predetermined time range, 2) ensuring matched data pair in said calibration set are no older than a predetermined value, 3) ensuring said calibration set has substantially distributed high and low matched data pair over said predetermined time range, and 4) allowing matched data pair only within a predetermined range of analyte values; and means for modifying said calibration set if such modification is required by said evaluation wherein the means for forming a calibration set further comprises determining a value for n, where n is greater than one and represents the number of matched data pair in the calibration set, and wherein the means for determining a value for n is determined as a function of the frequency of the received reference data points and signal strength over time. 36. The system of claim 20, further comprising means for determining a set of matched data pairs from said evaluation. 37. The system of claim 36, further comprising said means for repeating the step of creating a conversion function using said set of matched data pairs. 38. The system of claim 37, further comprising means for converting sensor data into calibrated data using said conversion function. 39. A computer system for calibrating a substantially continuous analyte sensor, the computer system comprising: a sensor data receiving module that receives a data stream comprising a plurality of time spaced sensor data points from a substantially continuous analyte sensor; a reference data receiving module that receives reference data from a reference analyte monitor, including two or more reference data points; a data matching module that forms one or more matched data pair by matching reference data to substantially time corresponding sensor data; a conversion function module that creates a conversion function using said one or more matched data pairs; a calibration evaluation module that evaluates one or more matched data pair, wherein evaluating said one or more matched data pairs includes at least one of 1) ensuring said one or more matched data pairs is within a predetermined time period, 2) ensuring said one or more matched data pairs is no older than a predetermined value, 3) ensuring said one or more matched data pairs have substantially distributed high and low matched data pairs over a predetermined time range, and 4) ensuring said one or more matched data pairs is within a predetermined range of analyte values, wherein said evaluation calibration module further evaluates at least one of a rate of change of the analyte concentration, a congruence of respective sensor and reference data in matched data pairs, and physiological changes, and wherein said conversion function module is programmed to re-create said conversion function if such modification is required by said calibration evaluation module. 40. The computer system of claim 39, wherein said calibration evaluation module evaluates an initial one or more matched data pairs. 41. The computer system of claim 39, wherein said calibration evaluation module evaluates one or more subsequently received matched data pairs. 42. The computer system of claim 39, wherein said calibration evaluation module evaluates a plurality of matched data pairs. 43. The computer system of claim 39, wherein said sensor data receiving module receives said data stream from an implantable analyte sensor. 44. The computer system of claim 39, wherein said sensor data receiving module receives an algorithmically smoothed data stream. 45. The computer system of claim 39, wherein said sensor data receiving module comprises programming to smooth said data stream. 46. The computer system of claim 39, wherein said reference data receiving module downloads reference data via a cabled connection. 47. The computer system of claim 39, wherein said reference data receiving module downloads reference data via a wireless connection. 48. The computer system of claim 39, wherein said reference data receiving module receives within a receiver internal communication from a reference analyte monitor integral with said receiver. 49. The computer system of claim 39, wherein said reference data receiving module receives reference data from a self monitoring of blood analyte. 50. The computer system of claim 39, wherein said conversion function module comprises programming that performs linear regression. 51. The computer system of claim 39, wherein said conversion function module comprises programming that performs non-linear regression. 52. The computer system of claim 42, wherein said conversion function module creates the conversion function based on between one matched data pair and six matched data pairs. 53. The computer system of claim 42, wherein said conversion function module creates the conversion function based on at least two matched data pairs. 54. A computer system for calibrating a substantially continuous analyte sensor, the computer system comprising: a sensor data receiving module that receives a data stream comprising a plurality of time spaced sensor data points from a substantially continuous analyte sensor; a reference data receiving module that receives reference data from a reference analyte monitor, including two or more reference data points; a data matching module that forms one or more matched data pair by matching reference data to substantially time corresponding sensor data; a calibration set module that forms a calibration set comprising at least one matched data pair; a conversion function module that creates a conversion function using said calibration set; a sensor data transformation module that converts sensor data into calibrated data using said conversion function; and a calibration evaluation module that evaluates said calibration set when said new matched data pair is provided, wherein evaluating said calibration set includes at least one of 1) ensuring matched data pair in said calibration set span a predetermined time period, 2) ensuring matched data pair in said calibration set are no older than a predetermined value, 3) ensuring said calibration set has substantially distributed high and low matched data pair over a predetermined time range, and 4) allowing matched data pair only within a predetermined range of analyte values, wherein said conversion function module is programmed to re-create said conversion function of such modification is required by said calibration evaluation module, wherein said programming for determining a value for n determines n as a function of the frequency of the received reference data points and signal strength over time, and wherein the calibration set module further comprises programming for determining a value for n, wherein n is greater than one and represents the number of matched data pairs in the calibration set. 55. The computer system of claim 39, wherein data matching module further comprises programming to form a set of matched data pairs responsive to said calibration evaluation. 56. The computer system of claim 55, wherein said conversion function module further comprises programming to create a conversion function based on said set of matched data pairs. 57. The computer system of claim 39 or 56, further comprising a sensor data transformation module comprising programming for converting sensor data into calibrated data using said conversion function. 58. A method for calibrating a glucose sensor, the method comprising: receiving a data stream from an analyte sensor, including one or more sensor data points; receiving reference data from a reference analyte monitor, including one or more reference data points; providing at least one matched data pair by matching reference analyte data to substantially time corresponding sensor data; creating a conversion function based on at least one matched data pair; and evaluating at least one of said matched data pairs, wherein evaluating comprises at least one of evaluating a rate of change of the analyte concentration, evaluating a congruence of respective sensor and reference data in a matched data pair, and evaluating physiological changes. 59. A computer system for calibrating a glucose sensor, the computer system comprising: a sensor data module that receives a data stream comprising a plurality of time spaced sensor data points from a substantially continuous analyte sensor; a reference input module that receives reference data from a reference analyte monitor, the reference data comprising one or more reference data points; a processor module that forms one or more matched data pairs by matching reference data to substantially time corresponding sensor data and subsequently forms a calibration set comprising said one or more matched data pairs; and a calibration evaluation module that evaluates one or more matched data pairs, wherein said evaluation calibration module evaluates at least one of a rate of change of the analyte concentration, a congruence of respective sensor and reference data in matched data pairs, and physiological changes. 60. The method of claim 58, wherein the step of matching reference analyte data to substantially time corresponding sensor data comprises determining a best matched pair at least in part by comparing a reference data point against a plurality of individual sensor values over a predetermined time period. 61. The method of claim 58, wherein the step of matching reference analyte data to substantially time corresponding sensor data is at least in part based on a time lag of at least about 5 minutes in the sensor data as compared to the reference data. 62. The method of claim 58, wherein the step of matching reference analyte data to substantially time corresponding sensor data comprises matching a reference data point with an average of a plurality of sensor data points over a predetermined time period. 63. The method of claim 58, wherein the step of evaluating at least one of said matched data pairs further comprises ensuring said at least one of said matched data pairs is within a predetermined range of analyte values. 64. The method of claim 58, wherein the step of evaluating at least one of said matched data pairs further comprises evaluating a clinical acceptability of a disparity between the reference data point and time corresponding sensor data point of said at least one of said matched data pairs. 65. The method of claim 58, wherein the step of evaluating at least one of said matched data pairs further comprises ensuring at least one of said matched data pairs is within a predetermined time range. 66. The method of claim 58, wherein the step of evaluating at least one of said matched data pairs further comprises ensuring at least one of said matched data pair is no older than a predetermined value. 67. The method of claim 58, wherein said at least one of said matched data pairs comprise two or more matched data pairs, and wherein the step of evaluating further comprises ensuring that the two or more matched pairs have substantially distributed values. 68. The system of claim 59, wherein the processor module is configured match reference data to substantially time corresponding sensor data at least in part by evaluating a best matched pair by comparing a reference data point against a plurality of individual sensor values over a predetermined time period. 69. The system of claim 59, wherein the processor module is configured match reference data to substantially time corresponding sensor data at least in part based on a time lag of at least about 5 minutes in the sensor data as compared to the reference data. 70. The system of claim 59, wherein the processor module is configured match reference data to substantially time corresponding sensor data is configured to match a reference data point with an average of a plurality of sensor data points over a predetermined time period. 71. The system of claim 59, wherein the calibration evaluation module is further configured to ensure one or more matched data pairs is within a predetermined range of analyte values. 72. The system of claim 59, wherein the calibration evaluation module is further configured to evaluate a clinical acceptability of a disparity between the reference data point and time corresponding sensor data point of one or more matched data pairs. 73. The system of claim 59, wherein the step of evaluating at least one of said matched data pairs further comprises ensuring said at least one of said matched data pairs is within a predetermined time range. 74. The system of claim 59, wherein the calibration evaluation module is further configured to ensure one or more matched data pairs is no older than a predetermined value. 75. The system of claim 59, wherein said one or more matched data pairs comprise two or more matched data pairs, and wherein the calibration evaluation module is further configured to ensure that the two or more matched data pairs have substantially distributed values.