Table 4.

Comparative analysis of glucose sensing performance in various body fluids toward wearable CGM

Properties	Blood	Urine	Sweat	Saliva	ISF	Tear
Glucose concentration	✓✓✓	✓✓	✓	✓	✓✓	✓
Correlation to blood glucose level	✓✓✓	✓✓	✓	✓	✓✓	✓
Reliability	✓✓✓	✓✓	✓	✓	✓✓	✓
Invasiveness	✓✓✓	‐	‐	‐	✓✓	✓
Sampling difficulty	✓✓✓	✓	✓	✓	✓✓	✓✓
Comfort	‐	✓	✓	‐	‐	‐
Pain or irritation during sampling	✓✓✓	‐	‐	‐	✓	✓
Safety	‐	✓	✓	‐	‐	‐
Real‐time, continuous measuring ability	‐	‐	✓	‐	✓	✓
Variation between sampling site	‐	‐	✓	‐	✓	‐
Sample homogeneity	✓	✓	‐	‐	✓	✓
Controlling ability of secretion rate	✓	✓	‐	‐	✓	‐
Sample reproduction	✓	‐	‐	✓	✓	‐
Requirement of stimulation or activity	‐	‐	✓	✓	‐	✓
Portability	✓	✓	✓	✓	✓	✓
Point‐of‐care suitability	✓	✓	✓	✓	✓	✓
Accuracy	✓✓✓	✓✓✓	✓	✓	✓✓	✓
Interference	✓	✓	✓	✓	✓	✓
Dependence of lifestyle, activity, diet,…	‐	‐	✓	✓	‐	✓
Wearable comfort	‐	‐	✓✓✓	✓✓	✓✓	✓
Instrument cost‐effectiveness	✓	✓	‐	‐	‐	‐

Level of property: (✓) low, (✓✓) moderate, (✓✓✓) high.