Patent ID: 8579854

Claim:
A system for the delivery of insulin to a patient, the system comprising: a continuous glucose sensor configured to sense glucose and to provide a sensor glucose level signal representative of the sensed glucose; an insulin delivery device configured to deliver insulin to a patient in response to delivery control signals; and a memory containing a glucose reference value therein, the glucose reference value representing an actual measured glucose level, the memory further containing a range of acceptable glucose sensor bias for acceptable glucose level control relative to the glucose reference value, wherein the range of glucose sensor bias encompasses a range having a lower end at which a sensor is biased toward sensing a lower level of glucose than actually exists and a higher end at which a sensor is biased toward sensing a higher level of glucose than actually exists, wherein the range of acceptable glucose sensor bias is asymmetrical about the glucose reference value; a controller programmed to store the glucose reference value in the memory, store the asymmetrical range of acceptable glucose sensor bias, receive the sensor glucose level signal, compare the sensor glucose level signal to the glucose reference value, calculate an amount of any sensor bias, compare any calculated sensor bias to the asymmetrical range of acceptable glucose sensor bias, and to provide a delivery control signal to the insulin delivery device to deliver insulin in a manner that accounts for the asymmetrical bias range of the glucose sensor whereby bias inaccuracy in the sensor may be tolerated with limited hyperglycemia while avoiding hypoglycemia.