An Amperometric Glucose Sensor Integrated into an Insulin Delivery Cannula: In Vitro and in Vivo Evaluation

W. Kenneth Ward, Gabriel Heinrich, Matthew Breen, Sheila Benware, Nicole Vollum, Kristin Morris, Chad Knutsen, Joseph D. Kowalski, Scott Campbell, Jerry Biehler, Mark S. Vreeke, Scott M. Vanderwerf, Jessica R. Castle, Robert S. Cargill

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Background: Labeling prohibits delivery of insulin at the site of subcutaneous continuous glucose monitoring (CGM). Integration of the sensing and insulin delivery functions into a single device would likely increase the usage of CGM in persons with type 1 diabetes. Methods: To understand the nature of such interference, we measured glucose at the site of bolus insulin delivery in swine using a flexible electrode strip that was laminated to the outer wall of an insulin delivery cannula. In terms of sensing design, we compared H2O2-measuring sensors biased at 600 mV with redox mediator-type sensors biased at 175 mV. Results: In H2O2-measuring sensors, but not in sensors with redox-mediated chemistry, a spurious rise in current was seen after insulin lis-pro boluses. This prolonged artifact was accompanied by electrode poisoning. In redox-mediated sensors, the patterns of sensor signals acquired during delivery of saline and without any liquid delivery were similar to those acquired during insulin delivery. Conclusion: Considering in vitro and in vivo findings together, it became clear that the mechanism of interference is the oxidation, at high bias potentials, of phenolic preservatives present in insulin formulations. This effect can be avoided by the use of redox mediator chemistry using a low bias potential.

Original languageEnglish (US)
Pages (from-to)226-236
Number of pages11
JournalDiabetes Technology and Therapeutics
Issue number4
StatePublished - Apr 2017


  • Continuous glucose monitoring
  • Continuous subcutaneous insulin infusion
  • Insulin delivery
  • Insulin delivery cannula
  • Type 1 diabetes

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology
  • Medical Laboratory Technology


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