1. Ideal Glucose Sensor in Critical Care
1. selective for glucose
2. a fast, predictable response to changing glucose concentrations.
3. depend on a reversible and reproducible signal to provide results; no cautery, drug interference
4. sensor fabrication must be reproducible and cheap on a large scale.
5. acceptable , easy to use, non-obtrusive to busy care-givers
Modified from

2. Ideal Glucose Sensor in Critical Care
Therefore, it should be
1. non-invasive
2. minimum calibration required, minimize fingersticks
3. real-time continuous information regarding glucose
4. alerts at times of hypoglycemia or, rapid glucose change.
Value increased if Continuous Glucose Monitoring integrated to implement Closed-Loop Control.
Minimize vagaries of inconsistent, imperfect human determination of insulin (other) delivery
Modified from

3. Sensor Improvements Over Time Clear
Chemistry
Outer membrane compatibility- ‘smart biomaterials’
Electronics
Optics
Miniaturization- nanotechnology
Signal processing
Manufacturing
Have improved accuracy, stability, sensitivity, specificity, robustness
But still no IDEAL SENSOR
Joseph, j. Diabetes,Science and Tech.,3:1309,2009

4. Glucose Sensors: A review of current and emerging technology
Subcutaneous
Electrochemical
Microdialysis
GLUCODAYglucose
taken ex vivo, only 1 calib/day
Continuous
Invasive
Intravenous
Fluorescent
Intravenous
*Non-Invasive CGM systems
Kromoscopy
Thermal infrared
Glucose Sensors
Photo-acoustic
Spectroscopy
Fluorescence
“sipper” autodraw
Optical
Optical coherence
tomography
Raman
spectroscopy
? In-hosp
Point sample
Lab / YSI
Scattering
spectroscopy
Mid-infrared
spectroscopy
Glucometer
Polarimetry
Near-infrared
spectroscopy
Optiscan
*Non-Invasive CGM systems- Near infrared spectroscopy, electrical impedance, physical changes
Value limited by low sensitivity, specificity, signal-noise ratio, unstable sensor-tissue interface
Most Hope in Future but
? Continuous enough
Electrochemical
Adapted from: Oliver NS, Toumazou C, Cass AEG, Johnston DG. Diab Med 2009, 26:

5. Accuracy Issues in Critical Care-Measuring
Need to be most accurate <80, but current sensors less accurate <80, and
Ideally, not have any errors when <80
Ideally, VO VALUES < 80
Point Values Assessed by
Clarke Error Grid or by
Consensus Error Grid
D,E; C,D,E
Unacceptable ie: sensor # = high,
real # = low