Background: The orthogonally redundant sensor (ORS) integrates two distinct glucose sensing technologies, electrochemical and optical fluorescence-based, with independent failure modes, potentially improving continuous glucose monitoring reliability.
Aim: To evaluate the performance of a progressively refined series of ORS prototypes.
Method: Eighteen adults with type 1 diabetes wore an investigational ORS and a non-redundant comparator sensor (NCS) concurrently for 48‒168 hours. Following sensor insertion, and later with a standardised meal, venous samples were collected for reference plasma glucose measurement at 30 minute and 15 minute intervals, respectively, over 4 hours. Between study visits, participants wore both sensors in an ambulatory setting and performed capillary blood glucose testing. Sensor glucose values were displayed only when trace characterisation algorithms deemed values to be sufficiently accurate. Glucose readings from both sensors were compared to plasma and capillary glucose levels.
Results: The ORS configuration was iteratively evolved resulting in incremental optical sensor improvements. Average sensor display time was higher for ORS than NCS (98.0% versus 94.6%). Benefits observed through orthogonal redundancy included increased sensor lifetime and reduced sensor artefact. Mean absolute relative difference (MARD) and compliance with international standard (ISO 15197:2003) accuracy metrics were similar for ORS and NCS. There was no irritation or infection at any sensor insertion sites.
Conclusion: Increasing ORS sensor display time resulted in improved sensor reliability without compromising accuracy. Combining optical and electrochemical sensing technologies is feasible, and potentially increases glucose sensing reliability which may facilitate artificial pancreas development.
We gratefully acknowledge funding from the Juvenile Diabetes Research Foundation and the Helmsley Charitable Trust.