TABLE 2.

Lin's concordance correlation analyses of the differences among the gold standard automated biochemistry analyzer serum glucose concentration, interstitial glucose concentration measured by the flash glucose monitoring system, and blood glucose concentration measured by the point‐of‐care glucometer

Type of sample	Examined methodology	Established methodology	Number of paired samples	ρ c (95% confidence interval)	Bias correction factor	Mean difference between methodologies ±SD (95% limits of agreement, mg/dL)
All samples	FGMS	ABA	139	0.96 (0.95‐0.97)	1.0	5.3 ± 31.6 (−56.6 to 67.2)
	FGMS	POCG	142	0.92 (0.89‐0.94)	0.97	23.0 ± 37.6 (−50.6 to 96.6)
	POCG	ABA	153	0.98 (0.97‐0.98)	0.99	20.4 ± 19.7 (−18.2 to 59.0)
All samples with hyperglycemia	FGMS	ABA	100	0.86 (0.80‐0.91)	0.99	7.0 ± 35.1 (−61.7 to 75.7)
	FGMS	POCG	103	0.74 (0.66‐0.82)	0.92	27.3 ± 42.0 (−55.0 to 109.7)
	POCG	ABA	112	0.94 (0.92‐0.96)	0.96	23.4 ± 20.7 (−17.1 to 63.9)
Samples with pronounced hyperglycemia	FGMS	ABA	85	0.80 (0.72‐0.87)	0.97	5.14 ± 37.2 (−67.7 to 78.0)
	FGMS	POCG	88	0.67 (0.56‐0.77)	0.90	26.6 ± 45.0 (−61.6 to 114.8)
	POCG	ABA	97	0.93 (0.90‐0.95)	0.95	24.8 ± 21.6 (−17.7 to 67.2)
Samples with normoglycemia	FGMS	ABA	33	0.70 (0.52‐0.87)	0.99	−2.0 ± 20.1 (−41.4 to 37.4)
	FGMS	POCG	33	0.71 (0.54‐0.87)	0.93	9.5 ± 18.2 (−26.1 to 45.2)
	POCG	ABA	34	0.70 (0.55‐0.85)	0.86	13.5 ± 15.2 (−16.2 to 43.3)
Samples with hypoglycemia	FGMS	ABA	6	0.33 (−0.02 to 0.68)	0.38	16.5 ± 7.4 (2.0‐31.0)
	FGMS	POCG	6	0.20 (−0.05 to 0.45)	0.23	22.3 ± 8.2 (6.3‐38.3)
	POCG	ABA	7	0.66 (0.37‐0.95)	0.68	6.3 ± 1.7 (2.9‐9.6)

Note: Hyperglycemia, pronounced hyperglycemia, normoglycemia, and hypoglycemia were defined based on automated biochemistry blood glucose concentrations >168, >250, ≥67 and ≤168, and <67 mg/dL, respectively.

Abbreviations: ABA, automated biochemistry analyzer measurement (serum); FGMS, flash glucose monitoring system (interstitial glucose); POCG, point‐of‐care glucometer measurement (whole blood); ρ _c, Pearson's correlation coefficient.