Insulin-sensitizing adipocyte-secreted protein (adipokine) that regulates glucose metabolism in liver and adipose tissue. Promotes glucose uptake in adipocytes and suppresses de novo glucose production in hepatocytes via the PI3K-Akt signaling pathway. Administration lead to reduction of blood glucose. Able to attenuate inflammation in fat tissue (PubMed:21849507, PubMed:22275362). Acts by activating the Akt signaling in hepatocytes and adipocytes. Not able to increase insulin-stimulated glucose uptake in adipocytes (PubMed:22942287). Acts by activating the MAP kinase. Increases insulin-stimulated glucose uptake in adipocytes (PubMed:22942287). Homomultimer; disulfide-linked (PubMed:22942287). Adipolin fC1QTNF12: homotrimer; disulfide-linked (PubMed:22942287). Adipolin gC1QTNF12: homodimer; disulfide-linked (PubMed:22942287). May interact with ERFE. In serum is the predominant form. Widely expressed, with high expression in subcutaneous and epididymal white adipose tissues and brown adipose tissue. Expressed in adipocytes (at protein level). During adipogenesis. Upon insulin treatment. Up-regulated in obeses mice. Transcription is activated by KLF3 and KLF15. Processed into Adipolin fC1QTNF12 and Adipolin gC1QTNF12 by FURIN (PubMed:22942287). Insulin enhances endogenous C1QTNF12 cleavage (PubMed:22942287). Belongs to the adipolin/erythroferrone family.