Continuous glucose monitors: accuracy issues and glycaemic management using alarms

Katherine Iscoe

    Research output: ThesisDoctoral Thesis

    568 Downloads (Pure)

    Abstract

    [Truncated abstract] Continuous glucose monitors (CGMs) provide a useful means to help stabilise blood glucose levels independently of the time of day or activity level. This is because CGMs provide continuous real-time estimates of glucose levels which can assist in the prevention of both hypo- and hyperglycaemia. However, the inaccuracy of the devices arising from both physiological and technological factors must be better understood for optimal use of CGMs in improving the daily management of blood glucose levels in individuals with type 1 diabetes mellitus (T1DM). Using the most current CGM available in Australia, the Paradigm 722 Real-Time (Medtronic Inc, Northridge, CA), the purpose of this thesis was to elucidate some of the factors that limit CGM’s accuracy and to devise strategies to better use CGMs despite these limitations. The first objective of this thesis was to examine whether the CGM’s intrinsic accuracy in the low glucose range improves if calibrations are performed at different concentrations in vitro. Our second objective was to evaluate the extent to which extended periods of wear affect the responses of both CGM accuracy and lag time to rapid changes in blood glucose levels. In addition, given that prolonged wear raises the issue of comfort, our objective was also to assess responses to sensor site of insertion. Finally, our last objective was to determine whether raising the CGM’s alarm to accommodate for the mismatch between CGM and blood glucose readings in anticipation of an exercise-induced rapid fall in glycaemia could be one condition where the incidence of hypoglycaemia may be reduced without triggering any false alarms. The first study examined whether CGM’s intrinsic accuracy improves if calibrations are performed at different glucose concentrations in vitro. In one experiment, we examined whether the glucose concentration at which the unit is calibrated affects accuracy at low and high glucose levels.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2012

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