Modular Closed-Loop Control Of Diabetes
S. D. Patek, L. Magni, E. Dassau, C. Hughes-Karvetski, C. Toffanin, G. De Nicolao, S. Del Favero, M. Breton, C. Dalla Man, E. Renard, H. Zisser, F. J. Doyle, III, C. Cobelli, and B. P. Kovatchev, on behalf of the International Artificial Pancreas (iAP) Study Group
Volume: 59, Issue: 11, Part: 1, Pages: 2986 – 2999, Abstract
Publication Year: 2012
Type 1 Diabetes (T1D) is an autoimmune disease that results in the destruction of pancreatic beta cells. Patients with T1D consequently have an insufficient supply of insulin, a hormone that allows glucose to be used as a fuel by the liver, muscle, and adipose cells of the body. Intensive treatment with multiple daily insulin injections or continuous insulin infusion from portable pumps can help maintain near-normal glycemia at the cost of symptomatic or even life threatening hypoglycemia (low blood sugar) due to eventual overdosing of insulin. Recent technological advances allowing wireless connectivity to glucose sensing and insulin delivery devices have renewed interest in automated closed-loop control of diabetes, i.e. the “Artificial Pancreas,” with the potential of minimizing incidence of both hypoglycemia and hyperglycemia, reducing the incidence of complications, and improving quality of life. In this paper we introduce a modular algorithmic architecture for closed-loop control of diabetes, providing details for a “control-to-range” system. The proposed architecture involves three modular layers that interact at different timescales: an event-driven device interface layer, assuring communication between components, a continuously operating safety layer, supervising all commands to the insulin pump, and a feedback control layer that adjusts insulin at regular intervals for optimal control. In this context, modularity allows for plug-and-play integration of algorithmic components, enhancing flexibility and adaptability, and facilitating standardization. Separating the functions of insulin recommendation and safety supervision allows for the stepwise introduction of and regulatory approval for algorithmic components, starting with subsystems for assured patient safety and followed by higher-layer components that serve to modify the patient’s insulin therapy rate in real-time. Clinical trials of the modular control-to-range system have demonstrated reduction of hypoglycemia associated with safety supervision alone and improved mean blood-glucose level with the addition of real-time control, cf. Breton, Farret, Bruttomesso et al., Diabetes, 61:2230-2237, 2012.