Methods for reducing false hypoglycemia alarm occurrence

Abstract

A system and method for reducing the number of hypoglycemic alarms presented to a user is presented. The system and methods include use of model based state estimation and variable-delayed threshold values to balance the risk of not presenting an alarm caused by an actual hypoglycemic state with the presentation of alarms caused by artifacts in the signals produced by a continuous glucose monitor.

1 . A system for monitoring the glucose level of a user, comprising:
 a continuous glucose monitor;   a processor configured to receive signals from the continuous glucose monitor and also adapted to analyze those signals in accordance with software commands, the software commands including commands to program at least a portion of the processor to operate as a state machine, the state machine having a first state when the signals from the continuous glucose monitor indicate a not hypoglycemic state and a second state when the signals indicate that a glucose value is below a selected threshold value.   
     
     
         2 . The system of  claim 1 , wherein the second state includes starting a timer to delay presentation of an alarm to the user, the delay determined by the glucose value. 
     
     
         3 . The system of  claim 1 , wherein the second state includes presenting an alarm to the user and requesting a confirmation measurement of glucose level when the glucose value is below a second selected threshold value that is lower than the first threshold value. 
     
     
         4 . The system of  claim 3 , wherein the second state includes recommending administration of rescue carbohydrates if the confirmation measurement glucose value is below a selected threshold. 
     
     
         5 . The system of  claim 2 , wherein an alarm is presented to the user at the expiration of the delay if the signal from the continuous glucose monitor indicates that the glucose value is still below the threshold value. 
     
     
         6 . A method for determining when to present a hypoglycemic alarm to a user of a continuous glucose monitor, comprising:
 providing a controller programmed to operate as a state machine;   providing signals from a continuous glucose monitor as input to the state machine;   wherein the state machine operates in accordance with the programming and the input to determine if an alarm is to be presented to the user indicating that an actual hypoglycemic condition exists.   
     
     
         7 . A system for monitoring the glucose level of a user, comprising:
 a continuous glucose monitor configured to transmit signals representative of a glucose value;   a processor configured to receive signals from the continuous glucose monitor and also adapted to analyze those signals in accordance with software commands, the software commands including commands to program at least a portion of the processor to operate as an alarm specificity optimizing system, the alarm specificity system having a first subsystem where temporal behavior of the signals from the continuous glucose monitor is used to maximize the specificity of a hypoglycemic event detection and assert a hypoglycemic alarm, and a second subsystem where one or more glucose level measurements is used to ensure whether or not the hypoglycemic event has been resolved.   
     
     
         8 . The system of  claim 7 , wherein optimization of the alarm specificity includes having the first subsystem starting one or more timers to delay presentation of an alarm to the user, wherein the delay for each timer is a function of the level of hypoglycemia indicated by signals received from the continuous glucose monitor. 
     
     
         9 . The system of  claim 7 , wherein the second subsystem includes requesting a confirmation measurement of glucose level when the first subsystem presents an alarm or when a value of a previous glucose level measurement is below a selected threshold value. 
     
     
         10 . The system of  claim 9 , wherein the second subsystem includes recommending administration of rescue carbohydrates if the confirmation measurement glucose value is below a selected threshold. 
     
     
         11 . The system of  claim 9 , wherein the second subsystem utilizes temporal glucose information and other relevant information to aid in minimizing false alarms by determining the appropriate amount of delay since the latest glucose level measurement that confirms a non-hypoglycemic event before the first subsystem can start detecting hypoglycemic events again. 
     
     
         12 . The system of  claim 8 , wherein an alarm is presented to the user at the expiration of the delay if the signal from the continuous glucose monitor indicates that the glucose value is still below the threshold value. 
     
     
         13 . The system of  claim 12 , wherein the delay can be zero if the glucose measurement is below a low glucose threshold value. 
     
     
         14 - 17 . (canceled)