The Application of the Insulin to C-Peptide Molar Ratio (ICPR) in Primary Screening for Insulin Antibodies in Type 2 Diabetes Mellitus Patients: A Further Quantitative Study on the Relationship Between ICPR and Insulin Antibodies

Figures & data

Table 1 Baseline Characteristics of the Included T2DM Patients ()

Group	N	Sex (M/F)	Age (Years)	BMI (kg/m^2)	HbA1c (%)	2h-ICPR	IA Titers (COI)
All	274	177/97	51.92±13.10	24.94±3.99	9.70±2.39	0.12±0.11	0.37±1.12
IA–	255	163/92	51.62±12.96	24.93±4.04	9.72±2.43	0.12±0.06	0.15±0.21
IA+	19	14/5	55.95±14.68	24.97±3.32	9.49±1.93	0.21±0.33	3.32±2.92
t-value	-	-	−1.392	−0.037	0.405	−3.866	−17.180
p-value	–	–	0.380	0.453	0.171	<0.001	<0.001

Abbreviations: BMI, body mass index; HbA1c, hemoglobin A1c; 2h-ICPR, 2-hour insulin to C-peptide molar ratio; IA, insulin antibody.

Table 2 OGTT Characteristics of All Included T2DM Patients ()

OGTT Profile	0 h	0.5 h	1 h	2 h
Glucose (mmol/L)	7.104±1.585	12.889±1.807	16.478±3.487	17.566±4.415
Insulin (pmol/L)	56.207±6.942	152.861±12.827	265.104±21.610	346.374±26.392
C-peptide (nmol/L)	0.629±0.212	1.051±0.038	1.601±0.063	2.481±0.204

Abbreviation: OGTT, oral glucose tolerance test.

Figure 1 Flowchart for the study.

Table 3 Univariate Linear Regression Analysis Between IAs with Age, 2h-ICPR, BMI and HbA1c by Karl Pearson’s Coefficient

Independent Variables	r-value	p-value
Age	0.163	0.007
2h-ICPR	0.259	0.001
BMI	0.007	0.907
HbA1c	0.092	0.129

Abbreviations: 2h-ICPR, 2-hour insulin to C-peptide molar ratio; BMI, body mass index; HbA1c, hemoglobin A1c.

Figure 2 Univariate linear regression analysis between IAs with Age, 2h-ICPR, BMI and HbA1c.

Notes: **p<0.01;***p<0.001.

Abbreviations: 2h-ICPR, 2-hour insulin to C-peptide molar ratio; BMI, body mass index; HbA1c, hemoglobin A1c.

Table 4 Coefficients of the Multiple Linear Regression Analysis of IA Titers by 2h-ICPR and Age

Model		Unstandardized Coefficients		t-value	p-value	95% CI for β		Collinearity Statistics
		β	Std. Error			Lower Bound	Upper Bound	Tolerance	VIF
1	(Constant)	−0.712	0.276	−2.580	0.010	−1.256	−0.169	-	-
	Age	0.014	0.005	2.866	0.004	0.004	0.024	1.000	1.000
	2h-ICPR	2.758	0.611	4.514	<0.001	1.555	3.962	1.000	1.000

Abbreviations: 2h-ICPR, 2-hour insulin to C-peptide molar ratio; CI, confidence interval.

Figure 3 Hypothesis testing of multiple linear regression of IAs by 2h-ICPR and age.

Table 5 ANOVA of Multiple Linear Regression Model Between IAs with Age and 2h-ICPR

Model^a	Sum of Squares	df	Mean Square	F-value	p-value
Regression	32.372	2	16.186	14.165	<0.001^b
Residual	309.664	271	1.143	–	–
Total	342.036	273	–	–	–

Notes: ^aDependent variable: IAs; ^bPredictors: (Constant), 2h-ICPR, age.

Abbreviations: ANOVA, analysis of variance; 2h-ICPR, 2-hour insulin to C-peptide molar ratio.

Figure 4 Estimates of multiple linear regression analysis of IAs by 2h-ICPR and age.

Notes: Multiple linear regression model: .

Abbreviation: ICPR2h, 2-hour insulin to C-peptide molar ratio (2h-ICPR).