title: Inpatient trial of an artificial pancreas based on multiple model probabilistic predictive control with repeated large unannounced meals.
abstract: BACKGROUND
  Closed-loop control of blood glucose levels in people with type 1 diabetes offers the potential to reduce the incidence of diabetes complications and reduce the patients' burden, particularly if meals do not need to be announced. We therefore tested a closed-loop algorithm that does not require meal announcement.
  
  
  METHODS
  A multiple model probabilistic predictive controller (MMPPC) was assessed on four patients, revised to improve performance, and then assessed on six additional patients. Each inpatient admission lasted for 32 h with five unannounced meals containing approximately 1 g/kg of carbohydrate per admission. The system used an Abbott Diabetes Care (Alameda, CA) Navigator(®) continuous glucose monitor (CGM) and Insulet (Bedford, MA) Omnipod(®) insulin pump, with the MMPPC implemented through the artificial pancreas system platform. The controller was initialized only with the patient's total daily dose and daily basal pattern.
  
  
  RESULTS
  On a 24-h basis, the first cohort had mean reference and CGM readings of 179 and 167 mg/dL, respectively, with 53% and 62%, respectively, of readings between 70 and 180 mg/dL and four treatments for glucose values <70 mg/dL. The second cohort had mean reference and CGM readings of 161 and 142 mg/dL, respectively, with 63% and 78%, respectively, of the time spent euglycemic. There was one controller-induced hypoglycemic episode. For the 30 unannounced meals in the second cohort, the mean reference and CGM premeal, postmeal maximum, and 3-h postmeal values were 139 and 132, 223 and 208, and 168 and 156 mg/dL, respectively.
  
  
  CONCLUSIONS
  The MMPPC, tested in-clinic against repeated, large, unannounced meals, maintained reasonable glycemic control with a mean blood glucose level that would equate to a mean glycated hemoglobin value of 7.2%, with only one controller-induced hypoglycemic event occurring in the second cohort.
authors.affiliation: 1 Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute , Troy, New York.
authors.forename: Fraser
authors.initials: F
authors.lastname: Cameron
authors.forename: Günter
authors.initials: G
authors.lastname: Niemeyer
authors.forename: Darrell M
authors.initials: DM
authors.lastname: Wilson
authors.forename: B Wayne
authors.initials: BW
authors.lastname: Bequette
authors.forename: Kari S
authors.initials: KS
authors.lastname: Benassi
authors.forename: Paula
authors.initials: P
authors.lastname: Clinton
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Buckingham
mesh_terms: D000328:Adult; D000465:Algorithms; D001786:Blood Glucose / Q000187:drug effects*; D015190:Blood Glucose Self-Monitoring; D015331:Cohort Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy*; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D005260:Female; D006442:Glycated Hemoglobin / Q000187:drug effects*; D006801:Humans; D007003:Hypoglycemia / Q000517:prevention & control*; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D007297:Inpatients; D007328:Insulin / Q000008:administration & dosage; D008297:Male; D062407:Meals; D015233:Models, Statistical; D019397:Pancreas, Artificial; D019518:Postprandial Period; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin; C517652:hemoglobin A1c protein, human