Development and validation of a risk assessment model for prediabetes in China national diabetes survey

Table 1 Characteristics of participants with available prediabetes risk factor data in the China National Diabetes and Metabolic Disorders Study population

Variable	All	Normal glucose tolerance	Prediabetes	P value
mean ± SD/n (%)	n = 40381	n = 33571	n = 6810
Age, yr	44 ± 13	43 ± 13	50 ± 13	< 0.001
Men	15848 (39.2)	13156 (39.2)	2692 (39.5)	0.6
Education
University or above	9375 (23.2)	8245 (24.6)	1130 (16.6)	< 0.001
Middle school	21800 (54.0)	18279 (54.4)	3521 (51.7)
Primary school	6656 (16.5)	5129 (15.3)	1527 (22.4)
Illiteracy	2550 (6.3)	1918 (5.7)	632 (9.3)
Residency, urban	25425 (63.0)	21294 (63.4)	4131 (60.7)	< 0.001
DM family history, yes	4736 (11.7)	3756 (11.2)	980 (14.4)	< 0.001
Ever smoker, yes	9874 (24.5)	8169 (24.3)	1705 (25.0)	0.22
WC, cm	81.1 ± 10.6	80.3 ± 10.4	85.4 ± 10.5	< 0.001
WC in men	84.8 ± 10.5	84.1 ± 10.2	88.5 ± 10.7
WC in women	78.7 ± 10.0	77.8 ± 9.8	83.4 ± 9.8
BMI, kg/m2	23.9 ± 3.6	23.6 ± 3.5	25.4 ± 3.7	< 0.001
Cholesterol, mmol/L	4.7 ± 1.0	4.6 ± 1.0	5.0 ± 1.0	< 0.001
Triglycerides, mmol/L	1.5 ± 1.1	1.4 ± 1.0	1.9 ± 1.3	< 0.001
HDLC, mmol/L	1.3 ± 0.3	1.3 ± 0.3	1.3 ± 0.3	< 0.001
LDLC, mmol/L	2.7 ± 0.8	2.7 ± 0.8	2.9 ± 0.8	< 0.001
SBP, mmHg	121.1 ± 18.6	119.5 ± 17.8	129.0 ± 20.7	< 0.001
DBP, mmHg	77.9 ± 11.2	77.2 ± 10.9	81.3 ± 11.6	< 0.001
Fasting plasma glucose, mmol/L	5.1 ± 0.6	4.9 ± 0.5	5.6 ± 0.7	< 0.001
2-h plasma glucose, mmol/L	6.1 ± 1.6	5.6 ± 1.1	8.3 ± 1.5	< 0.001

DM: Diabetes mellitus; BMI: Body mass index; SBP: Systolic blood pressure; DBP: Diastolic blood pressure; HDLC: High-density lipoprotein cholesterol; LDLC: Low-density lipoprotein cholesterol; WC: Waist circumference.

Table 2 Multivariable logistic regression for prediabetes in China National Diabetes and Metabolic Disorders Study¹

Variable	β coefficients	P value	OR (95%CI)
Intercept	-6.1358	< 0.0001	-
Age, yr	0.0274	< 0.0001	1.028 (1.025-1.030)
Middle school or higher education	-0.2032	< 0.0001	0.816 (0.766-0.870)
DM family history	0.3108	< 0.0001	1.364 (1.261-1.477)
Waist circumference ≥ normal upper limit	0.1959	< 0.0001	1.216 (1.134-1.305)
BMI	0.0761	< 0.0001	1.079 (1.069-1.089)
SBP	0.0117	< 0.0001	1.012 (1.010-1.013)

¹The initial set of risk factors for variable selection in logistic regression model: Age, gender, middle school or higher education, DM family history, waist circumference above normal upper limit, BMI, SBP, DBP. DM: Diabetes mellitus; BMI: Body mass index; SBP: Systolic blood pressure; DBP: Diastolic blood pressure.

Table 3 Risk scores of risk factors for prediabetes

Predictor	Categories	Reference value	Base reference	Estimates of beta coefficients	P value	Points
Intercept				-6.1358	< 0.0001
Age	20-29	24.5	24.5	0.0274	< 0.0001	0
	30-39	34.5	24.5	0.0274	< 0.0001	2
	40-49	44.5	24.5	0.0274	< 0.0001	4
	50-59	54.5	24.5	0.0274	< 0.0001	6
	60-69	64.5	24.5	0.0274	< 0.0001	8
	70-79	74.5	24.5	0.0274	< 0.0001	10
	80-100	90	24.5	0.0274	< 0.0001	13
Middle, college or higher education	0	0	0	-0.2032	< 0.0001	0
	1	1	0	-0.2032	< 0.0001	-1
DM family history	0	0	0	0.3108	< 0.0001	0
	1	1	0	0.3108	< 0.0001	2
Waist circumference greater than normal limit1	0	0	0	0.1959	< 0.0001	0
	1	1	0	0.1959	< 0.0001	1
BMI	< 18.5	17.8	21.2	0.0761	< 0.0001	-2
	18.5-23.9	21.2	21.2	0.0761	< 0.0001	0
	24.0-27.9	25.95	21.2	0.0761	< 0.0001	3
	≥ 28	30.9	21.2	0.0761	< 0.0001	5
SBP	< 120	105	125	0.0117	< 0.0001	-2
	120-129	125	125	0.0117	< 0.0001	0
	130-139	135	125	0.0117	< 0.0001	1
	140-159	150	125	0.0117	< 0.0001	2
	≥ 160	169	125	0.0117	< 0.0001	4

¹Waist circumference greater than normal limit: ≥ 90 for men and ≥ 85 for women for Asian population and ≥ 102 cm in men and ≥ 88 cm in women for Mexican American, other Hispanic, non-Hispanic White and Black populations. DM: Diabetes mellitus, BMI: Body mass index, SBP: Systolic blood pressure.