Diabetes Complications and Related Comorbidities Impair the Accuracy of FreeStyle Libre, a Flash Continuous Glucose Monitoring System, in Patients with Type 2 Diabetes

Figures & data

Table 1 Clinical Characteristics of Patients (n = 742)

Characteristic	n (%)/Media (quartile)
Age (years)	64 (55, 73)
Gender
Male	373 (50.3%)
Female	369 (49.7%)
BMI (kg/m^2)	24.23 (21.88, 24.23)
Ketone (mmol/L)	0.4 (0.2, 0.6)
Creatinine (umol/L)	77 (62, 99)
Total cholesterol (mmol/L)	4.37 (3.59, 5.25)
HDL cholesterol (mmol/L)	0.99 (0.83, 1.20)
24h microalbuminuria (mg/24h)	156.40 (98.75, 309.75)
Albumin (g/L)	38 (35, 41)
Diabetic nephropathy
Yes	231 (31.1%)
No	511 (68.9%)
Hypertension
Yes	395 (53.2%)
No	347 (46.8%)
Cardiovascular and cerebrovascular events
Yes	277 (37.3%)
No	465 (62.7%)
Insulin dose (U)	31 (0, 50)
Duration (years)	7.00 (1.00, 10.00)
Hyperglycemia
Yes	178 (24.0%)
No	564 (76.0%)
HbA1c (%)	8.8 (6.9, 11.2)
Hb (g/L)	126 (113, 141)
CO2CP (mmol/L)	23.9 (22.4, 25.6)
Triglycerides (mmol/L)	1.40 (0.97, 2.09)
LDL cholesterol (mmol/L)	2.70 (1.99, 3.51)
eGFR (mL/min)	84.60 (60.05, 104.50)
Plasma colloid osmotic pressure (mOsm/kg)	284.27 (281.00, 287.79)
Diabetic foot
Yes	45 (6.1%)
No	697 (93.9%)
Infection
Yes	180 (24.3%)
No	562 (75.7%)
DKA
Yes	27 (3.6%)
No	715 (96.4%)
Peripheral vascular disease
Yes	573 (77.2%)
No	169 (22.8%)

Notes: Data are expressed as n (%) or median (quartile, 25th and 75th percentiles); the definition of hypertension according to European Society of Cardiology/European Society of Hypertension guidelines.

Figure 1 The consistency and difference between FCGM readings and REF in patients. Bland-Altman plots (A); comparison of FCGM value and REF value (B); Bias, MARD, CV, 95% limit of agreement (C); difference according to the ISO 15197:2013 standard (D). Bias: mean relative difference between FCGM and REF (FCGM-REF)/REF; MARD: |FCGM-REF|/REF; CV: standard deviation of the relative difference between FCGM and REF. Lower 95% Limit of Agreement: Bias - 1.96 × CV; Upper 95% Limit of Agreement: Bias + 1.96 × CV.

Figure 2 Comparison of the distribution of paired reading in risk zone in SEG and PEG.

Table 2 Clinical Characteristics of Patients with SEG C/D Risk Zones

	Patients with C/D Risk Zone		Z/χ^2	P
	No (N=327)	Yes (N =415)
Age (years)	61 (52, 70)	65 (56, 75)	−3.916	<0.001
Gender
Male	176 (53.8)	197 (47.5)	−1.717	0.086
Female	151 (46.2)	218 (52.5)
Duration (years)	6.00 (0.75, 10.00)	9.00 (2.00, 11.00)	−3.423	0.001
Ketone (mmol/L)	0.4 (0.2, 0.6)	0.4 (0.3, 0.7)	−1.384	0.166
BMI (kg/m^2)	24.57 (22.27, 26.91)	23.98 (21.54, 27.07)	−1.176	0.240
HbA1c (%)	9.5 (7.6, 11.8)	8.1 (6.7, 10.9)	−4.947	<0.001
HgAb (g/L)	132 (121, 144)	122 (108, 136)	−6.664	<0.001
Creatinine (umol/L)	74 (60, 90)	80 (65, 110)	−3.541	<0.001
eGFR (mL/min)	89.89 (71.69, 108.24)	79.15 (55.19, 101.68)	−4.262	<0.001
Plasma colloid osmotic pressure (mOsm/kg)	284.59 (282.02, 288.00)	284.00 (280.22, 287.46)	−2.541	0.011
Total cholesterol (mmol/L)	4.55 (3.76, 5.39)	4.19 (3.42, 5.04)	−4.224	<0.001
TG (mmol/L)	1.55 (1.00, 2.28)	1.34 (0.95, 1.83)	−3.388	0.001
HDL cholesterol (mmol/L)	0.99 (0.83, 1.16)	1.00 (0.83, 1.22)	−0.867	0.386
LDL cholesterol (mmol/L)	2.86 (2.12, 3.61)	2.60 (1.92, 3.36)	−3.090	0.002
Albumin (g/L)	38 (36.2, 40.8)	37 (35, 40)	−3.107	0.002
24h microalbuminuria (mg/24h)	141.10 (92.00, 229.00)	172.80 (105.00, 364.45)	−3.209	0.001
Hypoglycemia events
Yes	54 (16.5%)	124 (29.9%)	−4.230	<0.001
No	273 (83.5%)	291 (70.1%)
Infection
Yes	48 (14.7%)	132 (31.8%)	−5.400	<0.001
No	279 (85.3%)	283 (68.2%)
DKA
Yes	7 (2.1%)	20 (4.8%)	2.204	0.028
No	320 (97.9%)	395 (95.2%)
Diabetic foot
Yes	9 (2.8%)	36 (8.7%)	−3.454	0.001
No	318 (97.2%)	379 (91.3%)
Cardiovascular and cerebrovascular events
Yes	100 (30.6%)	177 (42.7%)	−3.372	0.001
No	225 (69.4%)	238 (57.3%)
HBP
Yes	143 (43.7%)	252 (60.7%)	−4.602	<0.001
No	184 (56.3%)	163 (39.3%)
Insulin dose (U)	38 (7, 56)	24 (0, 45)	−5.163	<0.001

Note: Data are expressed as n (%) or median (quartile, 25th and 75th percentiles).

Table 3 Independent Factors Affect the Accuracy of FCGM

	B	SE	P	OR	95% CI for OR
Hb	−0.014	0.004	0.001	0.986	0.977	0.994
Hypoglycemia events	0.683	0.198	0.001	1.98	1.344	2.916
Infection	0.845	0.207	<0.001	2.328	1.553	3.491
Diabetic foot	0.978	0.411	0.017	2.658	1.187	5.951
Insulin dose	−0.014	0.003	<0.001	0.986	0.98	0.992
DKA	0.956	0.485	0.049	2.602	1.005	6.735
Hypertension^†
Grade 1	−0.064	0.348	0.854	0.938	0.474	1.855
Grade 2	0.639	0.228	0.005	1.895	1.213	2.961
Grade 3	0.476	0.194	0.014	1.609	1.099	2.355

Note: ^†Define hypertension grade according to European Society of Cardiology/European Society of Hypertension guidelines.