Saturable Insulin Absorption Model for Automated Delivery

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Solution Overview

Problem

Automated insulin delivery systems face challenges in accurately determining insulin absorption rates, leading to potential over-delivery due to delays and the formation of insulin depots, which can result in increased risk of over-delivery and erroneous blood glucose readings.

Innovation Solution

A drug delivery system that calculates an aggregate insulin-on-board amount based on individual estimates, determines residual insulin amounts, and adjusts subsequent calculations to account for saturated absorption rates, thereby optimizing insulin delivery rates and preventing over-delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If insulin delivery is increased to compensate for absorption delays, then blood glucose control is improved, but the risk of over-delivery increases due to saturated absorption rates and insulin depot formation

Engineering Contradiction:

Improveblood glucose controlVSAvoidover-delivery risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the absorption rate parameter from a constant or linearly increasing function to a saturable function that accounts for maximum absorption capacity. The model parameters (maximum absorption rate, saturation constant) are adjusted based on insulin-on-board amounts to reflect physiological saturation, preventing over-delivery while maintaining effective glucose control.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system implements feedback by continuously monitoring insulin-on-board amounts and using this information to adjust subsequent insulin delivery decisions. The saturable absorption model provides feedback on the actual insulin utilization rate, allowing the closed-loop system to adapt delivery rates and avoid over-correction.

Inventive Principle:

Principle #23Feedback

2Productivity

If the insulin absorption rate is assumed to increase indefinitely, then insulin utilization is maximized, but insulin depot formation occurs leading to delayed and unpredictable absorption

Engineering Contradiction:

Improveinsulin utilization rateVSAvoidabsorption delay

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent introduces parameter changes by implementing a saturable absorption model where the absorption rate parameter transitions from unlimited growth to a capped value. The model uses parameters such as maximum absorption rate and saturation constants to describe the transition from linear to plateaued absorption kinetics, preventing depot formation while maximizing utilization within physiological limits.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If traditional insulin-on-board heuristics are used, then the system is simple to operate, but accuracy is reduced due to failure to account for saturated absorption rates

Engineering Contradiction:

Improvesystem simplicityVSAvoidinsulin absorption accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent improves measurement precision by changing the mathematical parameters from simple linear decay to saturable absorption kinetics. The model incorporates parameters for maximum absorption rate and saturation constants, transforming the calculation from a crude heuristic to a physiologically accurate model while maintaining automated computation.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system provides a more accurate insulin delivery rate by accounting for saturated absorption, reducing the risk of over-delivery and improving the reliability of blood glucose monitoring.

Implementation Method 1

This approximated heuristic does not consider the possibility of a saturated rate of absorption

Methodology Applied

Scientific EffectSaturated absorption rate: Absorption (physical)

Data Source

PatentUS20240157055A1Maximum subcutaneous insulin absorption rates to calculate effective insulin-on-board in automated insulin delivery systems

Publication Date: 2024.05.16 INSULET CORP

AI summary

A drug delivery system including a memory storing programming code operable to enable delivery of insulin and a processor operable to execute the programming code. When executed, the programming code causes the processor to: calculate a first aggregate insulin-on-board amount for a user based on a plurality of individual insulin-on-board estimates made over a first period of time, determine that the first aggregate insulin-on-board amount is greater than a maximum depot formation threshold amount, determine a first residual amount of insulin remaining in the first aggregate insulin-on-board amount, increase a subsequent calculation of an individual insulin-on-board estimate based on the first residual amount of insulin, and utilize the subsequent calculation of the individual insulin-on-board estimate in a calculation of a second aggregate insulin-on-board amount over a second period of time.