title: Stress Testing of an Artificial Pancreas System With Pizza and Exercise Leads to Improvements in the System's Fuzzy Logic Controller.
abstract: BACKGROUND
  Under controlled conditions, the Dose Safety artificial pancreas (AP) system controller, which utilizes "fuzzy logic" (FL) methodology to calculate and deliver appropriate insulin dosages based on changes in blood glucose, successfully managed glycemic excursions. The aim of this study was to show whether stressing the system with pizza (high carbohydrate/high fat) meals and exercise would reveal deficits in the performance of the Dose Safety FL controller (FLC) and lead to improvements in the dosing matrix.
  
  
  METHODS
  Ten subjects with type 1 diabetes (T1D) were enrolled and participated in 30 studies (17 meal, 13 exercise) using 2 versions of the FLC. After conducting 13 studies with the first version (FLC v2.0), interim results were evaluated and the FLC insulin-dosing matrix was modified to create a new controller version (FLC v2.1) that was validated through regression testing using v2.0 CGM datasets prior to its use in clinical studies. The subsequent 17 studies were performed using FLC v2.1.
  
  
  RESULTS
  Use of FLC v2.1 vs FLC v2.0 in the pizza meal tests showed improvements in mean blood glucose (205 mg/dL vs 232 mg/dL, P = .04). FLC v2.1 versus FLC v2.0 in exercise tests showed improvements in mean blood glucose (146 mg/dL vs 201 mg/dL, P = .004), percentage time spent >180 mg/dL (19.3% vs 46.7%, P = .001), and percentage time spent 70-180 mg/dL (80.0% vs 53.3%, P = .002).
  
  
  CONCLUSIONS
  Stress testing the AP system revealed deficits in the FLC performance, which led to adjustments to the dosing matrix followed by improved FLC performance when retested.
authors.affiliation: Department of Pediatrics, University of Washington, Seattle, WA, USA Dose Safety, Inc, Seattle, WA, USA richardmausethmd@msn.com.
authors.forename: Richard
authors.initials: R
authors.lastname: Mauseth
authors.affiliation: Benaroya Research Institute, Seattle, WA, USA.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Lord
authors.affiliation: School of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Irl B
authors.initials: IB
authors.lastname: Hirsch
authors.affiliation: Dose Safety, Inc, Seattle, WA, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Kircher
authors.affiliation: Dose Safety, Inc, Seattle, WA, USA.
authors.forename: Don P
authors.initials: DP
authors.lastname: Matheson
authors.affiliation: Benaroya Research Institute, Seattle, WA, USA.
authors.forename: Carla J
authors.initials: CJ
authors.lastname: Greenbaum
mesh_terms: D000328:Adult; D000465:Algorithms; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D015190:Blood Glucose Self-Monitoring; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004041:Dietary Fats / Q000008:administration & dosage*; D054796:Drug Dosage Calculations; D004867:Equipment Design; D015444:Exercise; D005260:Female; D017143:Fuzzy Logic; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000009:adverse effects; D007328:Insulin / Q000008:administration & dosage* / Q000009:adverse effects; D007332:Insulin Infusion Systems; D008297:Male; D008422:Materials Testing; D019397:Pancreas, Artificial; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013312:Stress, Physiological; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D007004:Hypoglycemic Agents; D007328:Insulin
keywords: AP; artificial pancreas; closed loop; fuzzy logic