The Performance of an Orthogonally Redundant Glucose Sensor compared to a Simply Redundant Electrochemical Glucose Sensor in Adults with Type 1 Diabetes — ASN Events
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The Performance of an Orthogonally Redundant Glucose Sensor compared to a Simply Redundant Electrochemical Glucose Sensor in Adults with Type 1 Diabetes (#45)

Sybil A McAuley 1 2 , Tri T Dang 3 , Jodie C Horsburgh 1 , Anubhuti Bansal 3 , Glenn M Ward 1 2 , Alicia J Jenkins 1 , Richard J MacIsaac 1 2 , Rajiv V Shah 3 , David N O'Neal 1 2
  1. St Vincent's Hospital Melbourne, Melbourne, VIC
  2. University of Melbourne, Melbourne, VIC
  3. Medtronic Diabetes, Northridge, USA

Background: Continuous glucose monitoring system redundancy, combining multiple glucose sensing elements onto a single sensor, may improve accuracy and reliability. Simple redundancy involves multiple sensing elements utilising the same technology, whereas in orthogonal redundancy sensing elements utilise different technologies. The orthogonally redundant sensor (ORS) integrates two distinct glucose sensing technologies, electrochemical and optical, with independent failure modes, potentially improving continuous glucose monitoring reliability.

Aim: To compare the glucose sensing performance of a prototype ORS combining redundant electrochemical plus optical sensing to a simply redundant electrochemical comparator sensor (ECS) in adults with type 1 diabetes (T1D).

Method: Twenty-one adults with T1D wore an ORS and an ECS concurrently for 7 days. Following sensor insertion, and on Day 4 with a standard meal, venous samples were collected for reference plasma glucose measurement at standardised intervals over 3 and 4 hours, respectively. Between study visits, participants wore both sensors in an ambulatory setting and performed reference capillary blood glucose testing. Sensor glucose values are displayed only when algorithms determine the quality of the interstitial fluid glucose signal is adequate. Sensor glucose data were post-processed prospectively, using a combination of capillary blood and plasma glucose reference values.

Results: Accuracy metrics: mean absolute relative difference (MARD) for ORS vs. ECS overall was 10.4% vs. 11.0% (p=0.26), on Day 1 10.8% vs 16.3% (p<0.001), and on Day 2 10.2% vs. 13.7% (p<0.01). Reliability metrics: mean sensor display time was 95.5% for both ORS and ECS (p=1.0), and mean sensor lifetime was 6.5 days for ORS vs. 5.3 days for ECS (p=0.048). There was no sensor site irritation or infection.

Conclusion: ORS accuracy was better than ECS over the first 48 hours post-insertion. Premature sensor loss was less for ORS than ECS. Accuracy after the first 48 hours and the display time reliability of the surviving sensors are equivalent for ORS and ECS. There is potential benefit with orthogonal redundancy, though the technology will undergo continued development and further refinement of the optical sensor to fulfil that potential. Further sensor development is merited to optimise glucose sensing reliability, such as for use in ‘artificial pancreas’ systems.

  1. We gratefully acknowledge funding from the Juvenile Diabetes Research Foundation, the Helmsley Charitable Trust, and St Vincent’s Hospital Melbourne Research Endowment Fund.