The utility of diagnostic tests in the detection and prediction of glucose intolerance in the early and late postpartum period in women after gestational diabetes: a longitudinal cohort study

Table 1 Socio-demographic and medical characteristics of participants according to glucose tolerance categories based on oGTT criteria at 4–12 weeks postpartum

Variable	All (n = 967)	Normal (n = 670)	Pathological (n = 297)	P-value
Variable	Mean ± SD	Mean ± S D	Mean ± SD
Glucose tolerance defined by oGTT^a
Age (years)	33.0 ± 5.58	32.87 ± 5.70	33.32 ± 5.29	0.244
Gestational age at first GDM visit (weeks)	28.61 ± 3.69	29.02 ± 2.91	27.69 ± 4.93	< 0.001
Pre-pregnancy weight (kg)	69.53 ± 15.65	68.86 ± 15.30	71.05 ± 16.35	0.046
Pre-pregnancy BMI (kg/m²)	26.0 ± 5.59	25.63 ± 5.47	26.83 ± 5.76	0.002
Fasting glucose at first GDM visit (mmol/l)	5.17 ± 0.77	5.08 ± 0.71	5.35 ± 0.79	< 0.001
1 hr glucose at GDM diagnosis (mmol/l)	9.62 ± 1.87	9.44 ± 1.82	10.06 ± 1.88	< 0.001
2 hr glucose at GDM diagnosis (mmol/l)	7.85 ± 1.83	7.74 ± 1.74	8.11 ± 2.00	0.012
HbA1c at first GDM visit (%)	5.42 ± 0.41	5.32 ± 0.38	5.65 ± 0.41	< 0.001
Gestational age at delivery (weeks)	38.46 ± 3.10	38.54 ± 3.45	38.29 ± 2.08	0.242
Timing of early postpartum testing (weeks)	8.06 ± 5.21	7.94 ± 5.45	8.32 ± 4.63	0.299
Fasting glucose at 4–12 weeks pp (mmol/l)	5.03 ± 0.56	4.86 ± 0.37	5.42 ± 0.70	< 0.001
2 hr glucose at 4–12 weeks pp (mmol/l)	5.53 ± 1.68	5.08 ± 1.13	6.58 ± 2.20	< 0.001
HbA1c at 4–12 weeks pp (%)	5.34 ± 0.41	5.18 ± 0.30	5.70 ± 0.39	< 0.001
Fasting glucose at 1-year pp (mmol/l) (n = 322)	5.45 ± 0.65	5.33 ± 0.50	5.76 ± 0.90	< 0.001
HbA1c at 1-year pp (%) (n = 324)	5.29 ± 0.40	5.23 ± 0.33	5.48 ± 0.52	< 0.001
Fasting glucose at 3-year pp (mmol/l) (n = 69)	5.49 ± 0.55	5.42 ± 0.52	5.67 ± 0.57	0.086
HbA1c at 3-year pp (%) (n = 69)	5.26 ± 0.32	5.20 ± 0.32	5.41 ± 0.28	0.014

Variable	All (n = 967)	Normal (n = 670)	Pathological (n = 297)	P-value
Variable	n (%)	n (%)	n (%)	P-value
Nationality/ethnic origin
Switzerland	268 (27.7)	199 (29.7)	69 (23.2)
Europe + North America	317 (32.7)	237 (35.3)	80 (26.9)	0.001
Africa	170 (17.6)	108 (16.2)	61 (20.5)
Asia + western pacific	138 (14.3)	78 (11.6)	60 (20.2)
Latin America	43 (4.4)	29 (4.3)	14 (4.7)
Others	31 (3.3)	19 (2.8)	13 (4.4)
Parity
0	439 (45.4)	324 (48.3)	115 (38.7)	0.015
1	316 (32.6)	215 (32.2)	100 (33.7)
2	136 (14.0)	84 (12.5)	52 (17.5)
≥ 3	76 (8.0)	47 (7.0)	30 (10.1)
Previous history of GDM^b
Yes/no	70/897 (7.2/92.8)	33/637 (4.9/95.1)	37/260 (12.5/87.5)	< 0.001
Family history of diabetes^c
Yes/no	516/451 (53.4/46.6)	355/315 (52.9/47.1)	162/135 (54.5/45.5)	0.637
Glucose-lowering medication use during pregnancy
Yes/no	477/490 (49.3/50.7)	290/380 (43.2/56.8)	187/110 (63.0/37.0)	< 0.001
Breastfeeding at 4–12 weeks
Yes/no	787/180 (81.4/18.6)	549/121 (82.0/18.0)	238/39 (80.1/19.9)	0.499

^aNormal and Pathological glucose tolerance are according to oGTT criteria in the postpartum period. oGTT denotes oral glucose tolerance test; where normal glucose tolerance means FPG < 5.6 mmol/l or 2 hr glucose < 7.8 mmol/l and Pathological glucose tolerance FPG ≥ 5.6 mmol/l or 2 hr glucose ≥ 7.8 mmol/l. HbA1c denotes glycated hemoglobin. pp means postpartum
^bGDM denotes gestational diabetes mellitus (12.9% (n = 69) of women who were multiparous had previous history of GDM)
^cYes consists of those with first-degree relationship of the participant (e.g. mother, father, brother, sister, daughter, son) and those with second-degree kinship with the participant (e.g. grandparents, grandchildren, nephews, niece, half-brother, half-sister). All values are expressed as mean ± SD or % as indicated. n = 967 unless otherwise stated. Chi-square test was used for categorical variables and ANOVA for continuous variables

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