title: Time delay compensation for closed-loop insulin delivery systems: a simulation study.
abstract: Closed loop insulin therapy certainly represents the best possible approach to insulin replacement. However, present limitations preclude wider application of the so-called artificial pancreas. Therefore, a thorough understanding of these limitations is needed to design better systems for future long-term use. The present simulation study was design: to obtain better information on the impact of the measurement delay of currently available closed-loop devices both during closed-loop insulin delivery and blood glucose clamp studies, and to design and test a time delay compensator based on the method originally described by O.J. Smith. Simulations were performed on a Compaq Deskpro 486/25 personal computer under MS-DOS operating system using Simnon rel. 3.00 software. There was a direct relationship between measurement delay and amount of insulin delivered, i.e., the longer the delay the higher the insulin dose needed to control a rise in blood glucose; the closed-loop response in presence of a time delay was qualitatively impaired both during insulin delivery and blood glucose clamp studies; time delay compensation was effective in reducing the insulin dose and improving controller stability during the early phase of clamp studies. However, the robustness of a Smith's predictor-based controller should be carefully evaluated before implementation in closed-loop systems can be considered.
authors.affiliation: Istituto di Patologia Speciale Medica, University of Perugia, Italy.
authors.forename: G P
authors.initials: GP
authors.lastname: Reboldi
authors.forename: P D
authors.initials: PD
authors.lastname: Home
authors.forename: G
authors.initials: G
authors.lastname: Calabrese
authors.forename: P G
authors.initials: PG
authors.lastname: Fabietti
authors.forename: P
authors.initials: P
authors.lastname: Brunetti
authors.forename: M
authors.initials: M
authors.lastname: Massi Benedetti
mesh_terms: D003198:Computer Simulation; D003920:Diabetes Mellitus / Q000188:drug therapy; D004867:Equipment Design; D015309:Glucose Clamp Technique; D005950:Glucose Solution, Hypertonic / Q000008:administration & dosage; D005951:Glucose Tolerance Test; D006801:Humans; D015918:Infusion Pumps, Implantable; D007332:Insulin Infusion Systems; D013997:Time Factors
chemical_list: D005950:Glucose Solution, Hypertonic