title: The necessity of identifying the basal glucose set-point in the IVGTT for patients with Type 2 Diabetes.
abstract: BACKGROUND
  The model-based dynamic insulin sensitivity and secretion test (DISST) uses fasting glucose (G 0 ) as the basal glucose (G B ) concentration when assessing insulin sensitivity (SI). However, this model was developed in a healthy, normoglycaemic cohort. We sought to determine the suitability the DISST model has for individuals with established type 2 diabetes (T2D).
  
  
  METHODS
  14 participants with established T2D were recruited to take part in a dietary intervention study. Insulin-modified intravenous glucose tolerance tests (IM-IVGTT) were undertaken at week 0, 12 and 24 and were used with DISST model to identify G B . A total of 36 tests were conducted across 12 participants throughout the study. Measured G 0 and identified G B values were compared using a Kolmogorov-Smirnov (KS) and signed rank (RS) test for the cohort.
  
  
  RESULTS
  There were significant differences between the G 0 and identified G B values in this cohort (prs and pks < 0.0001), although both values were well correlated (R = 0.70). The residual plot demonstrates that the modified model captures the behaviour of the participants more accurately than the original model.
  
  
  CONCLUSIONS
  This analysis has shown that G B is an important variable for modelling the glycaemic behaviour in T2D. These findings suggest that the original DISST model, while appropriate for normoglycaemic cohorts, needs to model basal glucose level as a variable for assessing individuals with established T2D.
authors.affiliation: Department of Mechanical Engineering, Centre for Bio-Engineering, University of Canterbury, Private Bag 4800, Christchurch, 8054, New Zealand. azlan.othman@pg.canterbury.ac.nz.
authors.forename: Nor Azlan
authors.initials: NA
authors.lastname: Othman
authors.affiliation: Department of Mechanical Engineering, Centre for Bio-Engineering, University of Canterbury, Private Bag 4800, Christchurch, 8054, New Zealand. paul.docherty@canterbury.ac.nz.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Docherty
authors.affiliation: Department of Medicine, University of Otago, Wellington, 6242, New Zealand. Jeremy.Krebs@ccdhb.org.nz.
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Krebs
authors.affiliation: School of Medicine and Pharmacology Royal Perth Hospital Unit, The University of Western Australia, Perth, Western Australia, 6009, Australia. damon.bell@uwa.edu.au.
authors.forename: Damon A
authors.initials: DA
authors.lastname: Bell
authors.affiliation: Department of Mechanical Engineering, Centre for Bio-Engineering, University of Canterbury, Private Bag 4800, Christchurch, 8054, New Zealand. geoff.chase@canterbury.ac.nz.
authors.forename: J Geoffrey
authors.initials: JG
authors.lastname: Chase
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D003198:Computer Simulation; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000178:diet therapy / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D005215:Fasting / Q000097:blood; D005260:Female; D005947:Glucose / Q000008:administration & dosage / Q000493:pharmacokinetics; D005951:Glucose Tolerance Test; D006801:Humans; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D008954:Models, Biological
chemical_list: D001786:Blood Glucose; D007328:Insulin; D005947:Glucose