title: Feasibility of adjacent insulin infusion and continuous glucose monitoring via the Medtronic Combo-Set.
abstract: BACKGROUND
  Subcutaneously infused insulin may interfere with the function of nearby glucose-sensing electrodes and vice versa. The prototype of the Combo-Set device (Medtronic) incorporates a subcutaneous insulin delivery catheter and continuous glucose monitoring (CGM) sensor assembled on the same platform and separated by 11 mm. We aim to evaluate Combo-Set's insulin delivery and glucose-sensing functions.
  
  
  METHODS
  Ten subjects with type 1 diabetes wore a Combo-Set and a Sof-Sensor inserted subcutaneously in contralateral abdominal areas connected to iPro recorders (Medtronic) for 53.25 ± 0.75 h (mean ± standard deviation). The Combo-Set delivered insulin diluent except during meal tests on days 1 and 3 when insulin lispro was delivered as a meal bolus and postmeal basal. Venous plasma samples were collected at the following time points from meal start: 0, 30, 60, 120, and 180 min for insulin measurements. The accuracy of the Combo-Set sensors was evaluated and compared with that of the Sof-Sensor, with each referenced against capillary glucose values (Contour Link Meter, Bayer).
  
  
  RESULTS
  Accuracy of the Combo-Set sensor was comparable to that of the Sof-Sensor. Clarke error grid analysis showed that 97% of Combo-Set and 93% of Sof-Sensor values were in the A+B regions (p = .20, not significant). The Combo-Set showed the expected postbolus peak insulin time (67 ± 9 min, mean ± standard error). One "no delivery" alarm occurred during the 21 patient days of use.
  
  
  CONCLUSIONS
  A device providing for simultaneous adjacent placement of an insulin infusion catheter and a CGM sensor is feasible and functions within acceptable limits. The low "no delivery" alarm rate was similar to that of other infusion sets.
authors.affiliation: University of Melbourne, Department of Medicine, St. Vincent's Hospital, 4th Floor Clinical Sciences Building, Cnr of Princess and Regent Sts., Fitzroy 3065, Australia. dno@unimelb.edu.au
authors.forename: David N
authors.initials: DN
authors.lastname: O'Neal
authors.forename: Sumona
authors.initials: S
authors.lastname: Adhya
authors.forename: Alicia
authors.initials: A
authors.lastname: Jenkins
authors.forename: Glenn
authors.initials: G
authors.lastname: Ward
authors.forename: John B
authors.initials: JB
authors.lastname: Welsh
authors.forename: Gayane
authors.initials: G
authors.lastname: Voskanyan
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring / Q000295:instrumentation* / Q000379:methods; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D007332:Insulin Infusion Systems; D061268:Insulin Lispro / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D061268:Insulin Lispro