The correlation between ferritin levels and metabolic syndrome was stronger in studies corrected for CRP [OR = 1.90 (95% CI: 1.41–2.56; I2 = 82.4%)] versus studies not corrected for CRP [OR = 1.63 (95% CI: 1.47–1.81; I2 = 24.8%)]. This evidence concerns the gene CRP and metabolic syndrome.