Dynamic Basal Rate Limiter for Missed Meal Bolus Detection
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Solution Overview
Problem
Ambulatory insulin pumps often fail to automatically adjust insulin delivery when a user forgets to administer a meal bolus after consuming carbohydrates, leading to potential hyperglycemia due to inadequate basal rate increases.
Innovation Solution
A closed-loop diabetes therapy system that includes a pump mechanism, communications interface, and processor to automatically modify the basal insulin delivery rate based on continuous glucose monitor data, with a limiter function that increases the basal rate increase limit when high glucose levels and rapid glucose increases are detected, indicating a missed meal bolus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the basal rate increase limit is kept at a standard conservative level, then the system maintains safety and avoids excessive insulin delivery, but the system fails to respond aggressively enough when a user misses a meal bolus, leading to inadequate glucose control
Solution Approach 1:
The patent implements a dynamic limiter function that adjusts the basal rate increase limit based on real-time glucose data. When glucose levels are high and rising rapidly (indicating a missed meal bolus), the system dynamically increases the allowable basal rate increase beyond standard conservative limits. This dynamic adjustment allows the system to adapt its safety parameters to the current physiological state, enabling aggressive response when needed while maintaining safety under normal conditions.
2Device complexity
If the system uses a fixed limiter function for basal rate adjustments, then the control logic is simple and predictable, but the system cannot adequately respond to acute situations like missed meal boluses requiring aggressive insulin delivery
Solution Approach 1:
The patent transitions from a fixed limiter function to a dynamic one that automatically adjusts parameters based on glucose trends. The system monitors glucose levels and their rate of change, then modifies the basal rate increase limit accordingly. This dynamic approach maintains relatively simple control logic while dramatically improving the system's ability to handle acute situations like missed meal boluses.
Solution Approach 2:
The patent incorporates feedback mechanisms that continuously monitor glucose levels and their rate of change. This feedback information is used to adjust the limiter function parameters in real-time. When glucose is high and rising rapidly, the feedback triggers an increase in the allowable basal rate adjustment, enabling the system to respond appropriately to missed meal boluses while maintaining simple operation for the user.
3Productivity
If the basal rate increase limit is increased to respond to missed meal boluses, then the system can address hyperglycemia more effectively, but the risk of excessive insulin delivery and hypoglycemia increases
Solution Approach 1:
The patent uses dynamic parameter adjustment where the basal rate increase limit is temporarily elevated only when glucose data indicates a missed meal bolus (high glucose with rapid rise). This dynamic approach allows aggressive insulin delivery precisely when needed for hyperglycemia management while automatically returning to conservative limits when glucose levels are normal, thereby minimizing the risk of hypoglycemia.
Solution Approach 2:
The patent changes the operational parameters of the limiter function based on glucose state. When glucose levels and their rate of change indicate a missed meal bolus, the system modifies the basal rate increase limit parameter to allow more aggressive insulin delivery. When glucose levels are normal or declining, the parameter reverts to conservative values, thus managing hyperglycemia effectively while preventing hypoglycemia.
Data Source
AI summary
Disclosed herein are systems and methods for automated insulin delivery that aid in treatment when a user has eaten and has forgotten to deliver a meal bolus to counteract the carbohydrates consumed in the meal. The systems and methods disclosed herein can modify a limiter function that limits an amount by which a basal rate can be increased following a given glucose level reading in certain circumstances. For example, if the user's current or predicted future glucose level is high and the user's glucose level is increasing above a threshold rate, the limit can be increased from a standard limit. Such a glucose response may indicate that the user has eaten, but forgotten to instruct a meal bolus. By increasing the basal rate increase limit, the system can therefore react to and address the missed meal bolus.