Circulating levels of CTRP1, CTRP3, CTRP9, CTRP12 and CTRP15 were reduced in obese mice [9]; CTRP7 and CTRP9 were shown to be increased in patients with insulin resistance, type 2 diabetes mellitus or metabolic syndrome [10,11], while other CTRPs were reduced in such patients [12]. Here, C1QTNF9 is linked to metabolic syndrome.