Integrated insulin delivery system having delivery safety features
First Claim
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1. 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.
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Abstract
An integrated insulin delivery system having safety features for controlling medication delivery includes automatic resumption of basal rate after a particular event, such as termination of a bolus, expiration of a time period, delayed resumption after the bolus has terminated, IOB comparison, and others. Other safety features include overriding a delivery control that may result in hypoglycemia, terminating an extended bolus or temporary basal rate in view of a glucose signal indicating imminent carbohydrate deficiency, and controlling the delivery rate to take an asymmetrical bias range of a glucose sensor into account to avoid hypoglycemia.
25 Citations
21 Claims
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1. A system for the delivery of insulin to a patient, the system comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for the delivery of insulin to a patient, the system comprising:
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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, the memory also containing a maximum rate of insulin delivery; a controller programmed to provide a prompt to take a reference glucose measurement and store the value in the memory prior to the start of a closed-loop insulin delivery, to store the asymmetrical range of acceptable glucose sensor bias, to receive the sensor glucose level signal, to compare the sensor glucose level signal to the glucose reference value, to calculate an amount of any sensor bias, to compare any calculated sensor bias to the asymmetrical range of acceptable glucose sensor bias, to provide a delivery control signal to the insulin delivery device to deliver insulin if the calculated sensor bias falls within the asymmetrical range of acceptable sensor bias, the controller also programmed to calculate a rate of insulin delivery where the calculated bias falls within a high bias portion of the asymmetrical range of acceptable glucose bias, to compare the calculated rate of insulin delivery to the maximum rate of insulin delivery contained in the memory, and to control the insulin delivery device to deliver insulin at the lower rate of either the calculated rate of insulin delivery or the maximum rate of insulin delivery;
whereby bias inaccuracy in the sensor may be tolerated with limited hyperglycemia while avoiding hypoglycemia. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A system for the delivery of insulin to a patient, the system comprising:
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a 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, the memory also containing a maximum rate of insulin delivery; a controller programmed to provide a prompt to take a reference glucose measurement and store the value in the memory prior to the start of insulin delivery, to store the asymmetrical range of acceptable glucose sensor bias, to receive the sensor glucose level signal, to compare the sensor glucose level signal to the glucose reference value, to calculate an amount of any sensor bias, to compare any calculated sensor bias to the asymmetrical range of acceptable glucose sensor bias, to provide a delivery control signal to the insulin delivery device to deliver insulin if the calculated sensor bias falls within the asymmetrical range of acceptable sensor bias, the controller also programmed to calculate a rate of insulin delivery where the calculated bias falls within a high bias portion of the asymmetrical range of acceptable glucose bias, to compare the calculated rate of insulin delivery to the maximum rate of insulin delivery contained in the memory, and to control the insulin delivery device to deliver insulin at the lower rate of either the calculated rate of insulin delivery or the maximum rate of insulin delivery;
whereby bias inaccuracy in the sensor may be tolerated with limited hyperglycemia while avoiding hypoglycemia. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification