What, why and how to monitor blood glucose in critically ill patients

Table 3 Advantages and disadvantages of continuous glucose monitoring

Advantages	Disadvantages
Real-time interstitial glucose	Lag time of 15 min from blood glucose, in transdermal and subcutaneous devices (Caution if levels are fluctuating rapidly)
Deviation from arterial blood glucose is less than 20%	Direct vascular sampling continuous monitoring devices are still evolving
Provides long-term day-to-week blood glucose levels	Frequent calibration (2-3 times per day)
Reduced hypoglycaemic events	Biosensors have limited life (around 7 d)
Less labour intensive	Limited glycaemic range 40-400 mg/dL
Can reduce contact of care-givers reducing cross infections and risk to care-givers	Evolving clinical evidence (especially in critically ill patients)
	Invasive device, risk of infection when using intravenous devices