B. Wayne Bequette

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  Automated Insulin Delivery: An Overview of Models and Algorithms
  B. Wayne Bequette

  Pursuit of a closed-loop artificial pancreas that automatically controls the blood glucose of individuals with type 1 diabetes has intensified during the past decade. Here we discuss the recent progress and challenges in the major steps towards a closed-loop system. Continuous insulin infusion pumps have been widely available for over two decades, but ‘‘smart pump’’ technology has made the devices easier to use and more powerful. Continuous glucose monitoring (CGM) technology has improved and the devices are more widely available. Physiological models that include subcutaneously delivered insulin pharmacokinetics and pharmacodynamics enable extensive simulated clinical trials using proposed closed-loop algorithms before testing in human clinical trials.

  
  

  A number of approaches are currently under study for fully closed-loop systems; most manipulate only insulin, while others manipulate insulin and glucagon. Algorithms include on–off (for prevention of overnight hypoglycemia), proportional–integral–derivative (PID), model predictive control (MPC) and fuzzy logic based learning control. Two major disturbances include meals and exercise. While feedforward action using a “meal announcement� is desirable it places an addition burden on individuals, so we review techniques for meal detection/prediction; similarly, we review exercise detection methods. Finally, we examine fault detection algorithms for insulin infusion set failure and sensor signal attenuation.