Table 3.

Subgroup analysis to assess the magnesium concentrations in subjects with prediabetes.

Sub grouped by	No	WMD (95% CI)	P-value	P-Heterogeneity	I2 (%)	P- between subgroup heterogeneity
Publication year
≤ 2010	2	− 0.02 (− 0.06, 0.02)	0.318	< 0.001	88.4%	0.362
> 2010	8	− 0.12 (− 0.14, -0.09)	< 0.001	< 0.001	97.8%
Sample
Serum	9	− 0.10 (− 0.12, − 0.07)	< 0.001	< 0.001	97.3%	< 0.001
Plasma	1	− 0.03 (− 0.04, -0.02)	< 0.001	–	0%
Study design
Case–control	3	− 0.25 (− 0.45, -0.05)	0.016	< 0.001	98.6%	< 0.001
Cross- sectional	6	− 0.09 (− 0.11, − 0.06)	< 0.001	< 0.001	95.1%
Nested case–control	1	− 0.07 (− 0.86, 0.72)	0.863	–	0%
Region
US	2	0.00 (− 0.20, 0.20)	1.00	1.00	0%	< 0.001
European	2	− 0.35 (− 0.62, 0.07)	0.015	< 0.001	87.3%
Others	6	− 1.09 (− 1.57, − 0.61)	< 0.001	< 0.001	94.7%
Quality score
High	7	− 0.87 (− 1.29, − 0.45)	< 0.001	< 0.001	94.2%	0.02
Moderate	3	− 0.37 (− .0.61, − 0.13)	0.002	< 0.001	84.7%
Comparability
Complete adjustment	4	− 0.53 (− 0.91, − 0.15)	0.006	< 0.001	89.8%	0.05
No or incomplete adjustment	6	− 0.74 (− 1.08, − 0.40)	< 0.001	< 0.001	93.8%

WMD weighted mean difference.