title: Multivariable adaptive closed-loop control of an artificial pancreas without meal and activity announcement.
abstract: BACKGROUND
  Accurate closed-loop control is essential for developing artificial pancreas (AP) systems that adjust insulin infusion rates from insulin pumps. Glucose concentration information from continuous glucose monitoring (CGM) systems is the most important information for the control system. Additional physiological measurements can provide valuable information that can enhance the accuracy of the control system. Proportional-integral-derivative control and model predictive control have been popular in AP development. Their implementations to date rely on meal announcements (e.g., bolus insulin dose based on insulin:carbohydrate ratios) by the user. Adaptive control techniques provide a powerful alternative that do not necessitate any meal or activity announcements.
  
  
  METHODS
  Adaptive control systems based on the generalized predictive control framework are developed by extending the recursive modeling techniques. Physiological signals such as energy expenditure and galvanic skin response are used along with glucose measurements to generate a multiple-input-single-output model for predicting future glucose concentrations used by the controller. Insulin-on-board (IOB) is also estimated and used in control decisions. The controllers were tested with clinical studies that include seven cases with three different patients with type 1 diabetes for 32 or 60 h without any meal or activity announcements.
  
  
  RESULTS
  The adaptive control system kept glucose concentration in the normal preprandial and postprandial range (70-180 mg/dL) without any meal or activity announcements during the test period. After IOB estimation was added to the control system, mild hypoglycemic episodes were observed only in one of the four experiments. This was reflected in a plasma glucose value of 56 mg/dL (YSI 2300 STAT; Yellow Springs Instrument, Yellow Springs, OH) and a CGM value of 63 mg/dL).
  
  
  CONCLUSIONS
  Regulation of blood glucose concentration with an AP using adaptive control techniques was successful in clinical studies, even without any meal and physical activity announcement.
authors.affiliation: Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL 60616, USA.
authors.forename: Kamuran
authors.initials: K
authors.lastname: Turksoy
authors.forename: Elif Seyma
authors.initials: ES
authors.lastname: Bayrak
authors.forename: Lauretta
authors.initials: L
authors.lastname: Quinn
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Littlejohn
authors.forename: Ali
authors.initials: A
authors.lastname: Cinar
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001786:Blood Glucose / Q000378:metabolism*; D015190:Blood Glucose Self-Monitoring; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy; D004040:Dietary Carbohydrates; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D006943:Hyperglycemia / Q000097:blood* / Q000188:drug therapy; D007003:Hypoglycemia / Q000097:blood* / Q000188:drug therapy; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000008:administration & dosage / Q000097:blood*; D008297:Male; D062407:Meals; D019397:Pancreas, Artificial; D019518:Postprandial Period; D011237:Predictive Value of Tests; D015203:Reproducibility of Results
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin; C517652:hemoglobin A1c protein, human
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