Table 6.

Bias analysis of cross-sectional studies

DM/MetS	Cross-sectional	Newcastle-Ottawa quality assessment scale
	Study	Selection (five stars total)	Comparability (two stars total)	Outcome (three stars total)	Total (out of 10)
DM	Meydan et al 30	0	0	**	2
	Taylor et al 27	**	**	**	6
	Akoudad et al 29	***	**	**	7
	Weinberg et al 33	***	**	**	7
MetS	Rendina et al 34	***	*	***	7
	West et al 35	****	**	**	8
	Jeong et al 37	***	**	***	8
	Kim et al 38	***	**	***	8
	Lee et al 39	**	*	***	6

DM, diabetes mellitus; MetS, metabolic syndrome.