Establishment and evaluation of a risk prediction model for gestational diabetes mellitus

Table 1 Comparison of general data between the two groups of patients, n (%)

Items	GDM group (n = 197)	Non-GDM group (n = 209)	Statistics	P value
Age (yr)	31.57 ± 3.94	30.794 ± 4.05	1.965	0.051
Body height (cm)	159.67 ± 5.91	160.38 ± 4.95	1.351	0.189
Occupation			2.246	0.134
Regular work	49 (24.87)	66 (31.58)
No regular work	148 (75.13)	143 (68.42)
Education level			4.790	0.091
Junior high school and below	22 (11.17)	18 (8.61)
High school or technical secondary school	19 (9.64)	35 (16.75)
College undergraduate and above	156 (79.19)	156 (74.64)
Marital status			2.884	0.092
Primary marriage	169 (85.79)	166 (79.43)
Remarriage	28 (14.21)	43 (20.57)
Monthly income (yuan/month)			0.878	0.349
< 3000	36 (18.27)	46 (22.01)
≥ 3000	161 (81.73)	163 (77.99)
Family history of DM			22.357	< 0.001
Yes	49 (24.87)b	16 (7.66)
No	148 (75.13)b	193 (92.34)
Family history of hypertension			0.105	0.746
Yes	38 (19.29)	43 (20.57)
No	159 (80.71)	166 (79.43)
GDM			28.400	< 0.001
Yes	50 (25.38)b	13 (6.22)
No	147 (74.62)b	196 (93.78)
Parity			1.049	0.306
Plurality	91 (46.19)	86 (41.15)
Primiparity	106 (53.81)	123 (58.85)
PCOS			0.398	0.528
Yes	9 (4.57)	7 (3.35)
No	188 (95.43)	202 (96.65)
Giant infants			19.015	< 0.001
Yes	35 (17.77)b	9 (4.31)
No	162 (82.23)b	200 (95.69)
Pre-pregnancy weight (kg)	57.11 ± 9.58a	54.68 ± 7.26	2.898	0.004
Pre-pregnancy BMI (kg/m2)	24.11 ± 4.08b	21.25 ± 2.63	8.439	< 0.001
History of abortion			1.106	0.293
Yes	70 (35.53)	64 (30.62)
No	127 (64.47)	145 (69.38)
Cesarean section history			0.878	0.349
Yes	35 (17.77)	30 (15.23)
No	162 (82.23)	179 (84.77)
History of preterm birth			1.872	0.171
Yes	51 (25.89)	67 (32.06)
No	146 (74.11)	142 (67.94)
History of stillbirth			0.212	0.645
Yes	4 (2.03)	3 (1.44)
No	193 (97.97)	206 (98.56)
Hypertension			14.325	< 0.001
Yes	35 (17.77)b	12 (5.74)
No	162 (82.23)b	197 (94.26)
Erythrocytes (× 1012/L)	4.31 ± 0.41	4.27 ± 0.39	0.994	0.321
Hb (g/L)	128.77 ± 9.03b	121.34 ± 10.34	7.687	< 0.001
Urea (mmol/L)	2.94 ± 0.66	2.87 ± 0.65	1.079	0.281
Creatinine (μmol/L)	44.71 ± 6.81	45.38 ± 5.82	-1.070	0.285
Uric acid (μmol/L)	244.18 ± 54.53	234.62 ± 44.62	1.938	0.053
Triglyceride (mmol/L)	1.69 ± 0.56b	1.43 ± 0.69	4.058	< 0.001
Serum ferritin (ng/mL)	73.96 ± 18.36b	53.29 ± 15.30	12.350	< 0.001
First-trimester fasting hyperglycemia (mmol/L)	5.06 ± 0.47b	4.40 ± 0.71	10.971	< 0.001

^aP < 0.05 vs non-gestational diabetes mellitus (GDM) group.

^bP < 0.001 vs non-GDM group. BMI: Body mass index; DM: Diabetes mellitus; GDM: Gestational diabetes mellitus; Hb: Hemoglobin; PCOS: Polycystic ovary syndrome.

Table 2 Variable assignment

Variables	Assignment
Whether GDM occurred (dependent variable)	Yes = 1, no = 0
GDM	Yes = 1, no = 0
Hypertension	Yes = 1, no = 0
Giant infant	Yes = 1, no = 0
Family history of DM	Yes = 1, no = 0
Hb	Original value input
Pre-pregnancy BMI	Original value input
Triglyceride	Original value input
Serum ferritin	Original value input
First-trimester fasting hyperglycemia	Original value input

BMI: Body mass index; DM: Diabetes mellitus; GDM: Gestational diabetes mellitus; Hb: Hemoglobin.

Table 3 Multivariate logistic regression analysis results of gestational diabetes mellitus

Items	β	SE	Wald	P valuea	OR (95%CI)
Family history of DM	1.340	0.472	8.061	0.005	3.818 (1.514-9.626)
Hypertension	1.674	0.643	6.772	0.009	5.335 (1.512-18.825)
GDM	1.201	0.519	5.353	0.021	3.323 (1.201-9.192)
Giant infant	2.269	0.647	12.312	< 0.001	2.653 (1.284-5.483)
Pre-pregnancy BMI (kg/m2)	0.233	0.055	18.059	< 0.001	1.263 (1.134-1.406)
Hb (g/L)	0.071	0.018	14.867	< 0.001	1.073 (1.035-1.112)
Triglyceride (mmol/L)	0.792	0.249	10114	0.001	2.207 (1.355-3.596)
Serum ferritin (ng/mL)	0.070	0.010	44.508	< 0.001	1.072 (1.050-1.094)
First-trimester fasting hyperglycemia (mmol/L)	1.887	0.350	29.110	< 0.001	6.602 (3.326-13.105)

^aP < 0.05 was considered significant. BMI: Body mass index; DM: Diabetes mellitus; GDM: Gestational diabetes mellitus; Hb: Hemoglobin; SE: Standard error; OR: Odd ratio; CI: Confidence interval.

Table 4 Prediction performance evaluation results of the nomogram model and random forest model (%)

Prediction model		Sensitivity	Specificity	AUC (95%CI)
Nomogram model	Training set	74.1	87.6	0.883 (0.846-0.921)
	Validation set	81.0	81.2	0.850 (0.782-0.918)
Random forest model	Training set	91.4	84.8	0.950 (0.927-0.973)
	Validation set	89.7	89.7	0.918 (0.868-0.967)

AUC: Area under the curve; CI: Confidence interval.