Adiponectin gene polymorphisms and risk of gestational diabetes mellitus: A meta-analysis

Table 1 Quality assessment of included case control studies using the Newcastle-Ottawa scale

Author	Yr	Selection				Comparability		Exposure			Score
		Case definition	Case representativeness	Control selection	Control definition	Important confounders	Every confounders	Ascertainment	Consistency	Non-response rate
Low et al[7]	2011	1	1	0	1	1	0	1	1	1	7
Takhshid et al[2]	2015	1	1	1	1	0	0	1	1	1	7
Daher et al[8]	2011	1	1	1	1	1	0	1	1	1	8
Han et al[4]	2012	1	1	0	1	1	0	1	1	1	7
Gao et al[10]	2016	1	1	1	1	1	0	1	1	1	8
Luan et al[13]	2015	1	1	1	1	1	0	1	1	1	8
Li et al[12]	2017	1	1	1	1	1	0	1	1	1	8
Li et al[11]	2013	1	1	1	1	0	0	1	1	1	7
Zhang et al[14]	2014	1	1	1	1	1	0	1	1	1	8
Beltcheva et al[1]	2014	1	1	0	1	1	0	1	1	1	7
Pawlik et al[3]	2017	1	1	1	1	0	0	1	1	1	7
Chen et al[15]	2011	1	1	1	1	0	0	1	1	1	7
Wang et al[16]	2016	1	1	1	1	0	0	1	1	1	7

The quality evaluation content mainly includes three aspects: case selection, baseline comparability, and exposure factors with nine evaluation items. If the evaluation item is met, 1 point is obtained, otherwise 0, and the score ranges from 0 to 9.

Table 2 Detailed characteristics of all eligible studies for the association between ADIPOQ single nucleotide polymorphism and gestational diabetes mellitus

SNP	Author	Yr	Country	Ethnicity	Matching criteria	Method	Sample size		Genotype1		HWE
							Case	Control	Case	Control
+45T/G	Low et al[7]	2011	Malaysia	Asian	NR	Taq PCR	26	53	11/13/2	35/17/1	0.51
	Takhshid et al[2]	2015	Iran	Asian	Age	PCR-RELF	65	70	37/28/0	54/16/0	0.28
	Daher et al[8]	2011	Brazil	SA	Race	PCR-RELF	79	169	61/15/3	134/32/3	0.51
	Han et al[4]	2012	China	Asian	NR	PCR-RELF	152	120	63/71/18	64/50/6	0.34
	Gao et al[10]	2016	China	Asian	Age, GW	PCR-RELF	150	150	59/66/25	81/57/12	0.66
	Luan et al[13]	2015	China	Asian	Age, GW	NR	60	60	33/21/6	29/26/5	0.81
	Li et al[12]	2017	China	Asian	Age, GW	PCR-RELF	130	130	53/63/14	63/60/7	0.13
	Li et al[11]	2013	China	Asian	NR	Sequencing	264	172	134/113/17	97/66/9	0.6
	Zhang et al[14]	2014	China	Asian	Age, BMI, GW	PCR-RELF	98	135	38/43/17	73/51/11	0.62
+276G/T	Han et al[4]	2012	China	Asian	NR	PCR-RELF	152	120	12/66/74	11/53/56	0.34
	Gao et al[10]	2016	China	Asian	Age, GW	PCR-RELF	150	150	15/69/66	15/60/75	0.66
	Luan et al[13]	2015	China	Asian	Age, GW	NR	60	60	7/26/27	3/25/32	0.81
	Li et al[12]	2017	China	Asian	Age, GW	PCR-RELF	130	130	64/58/8	60/56/14	0.13
	Zhang et al[14]	2014	China	Asian	Age, BMI, GW	PCR-RELF	98	135	10/45/43	13/54/68	0.62
-11377C/G	Beltcheva et al[1]	2014	Bulgaria	European	Age, BMI	TaqMan	130	130	80/44/6	66/50/14	0.34
	Pawlik et al[3]	2017	Poland	European	NR	TaqMan	204	207	92/91/21	115/75/17	0.34
	Daher et al[8]	2011	Brazil	SA	race	PCR-RELF	79	169	54/20/5	105/50/13	0.05
	Chen et al[15]	2011	China	Asian	NR	PCR-RELF	103	97	55/43/5	50/38/9	0.65
	Wang et al[16]	2016	China	Asian	NR	PCR-RELF	206	189	107/84/15	106/73/10	0.57

¹Genotype is presented as wild type/heterozygous/homozygous. ADIPOQ: Adiponectin; GDM: Gestational diabetes mellitus; SNP: Single nucleotide polymorphism; SA: South American; GW: Gestational week; PCR-RELF: Polymerase chain reaction-restriction fragment length polymorphism; BMI: Body mass index; HWE: Hardy-Weinberg equilibrium; NR: Not reported.

Table 3 Main results of the pooled odds ratios in meta-analysis for the association between ADIPOQ polymorphisms and gestational diabetes mellitus

SNP	N	Sample size		Allelic model		Dominant model		Recessive model
		Case	Control	OR (95%CI)	P	OR (95%CI)	P	OR (95%CI)	P
+45T/G
Total	10	1024	1059	1.45 (1.26-1.67)	0.000a	1.50 (1.25-1.79)	0.000a	2.00 (1.42-2.84)	0.000a
Subgroup
Ethnicity
Asian	8	945	890	1.47 (1.27-1.70)	0.000a	1.54 (1.27-1.85)	0.000a	2.00 (1.43-2.85)	0.000a
SA	1	79	169	1.21 (0.68-2.41)	0.510	1.13 (0.59-2.15)	0.710	2.18 (0.43-11.07)	0.350
+276G/T
Total	5	590	595	0.88 (0.74-1.05)	0.158	0.91 (0.65-1.26)	0.561	0.82 (0.64-1.05)	0.118
-11377C/G
Total	5	722	791	0.96 (0.72-1.26)	0.750	1.00 (0.73-1.37)	0.980	0.90 (0.61-1.32)	0.570
Subgroup
Ethnicity
Asian	2	309	286	1.04 (0.77-1.41)	0.800	1.09 (0.79-1.50)	0.600	0.97 (0.51-1.86)	0.930
SA	1	79	168	0.80 (0.50-1.29)	0.360	0.77 (0.44-1.36)	0.370	0.81 (0.28-2.34)	0.690
European	2	334	337	0.94 (0.45-1.96)	0.870	1.00 (0.42-2.33)	0.990	0.87 (0.51-1.49)	0.610

^aP < 0.01. ADIPOQ: Adiponectin; SA: South American; GDM: Gestational diabetes mellitus; SNP: Single nucleotide polymorphism; N: Number of studies; OR: Odds ratio; CI: Confidence interval; NA: Not assessable.