Human Visfatin is an adipokine and is produced by visceral adipose tissue. Visfatin is a protein and was isolated from visceral fat deposits. It is a 55k D protein and belongs to the NAPRTase family.  Visfatin is known to have insulin-mimetic activities. Visfatin poses a hypoglycemic effect by its interaction with insulin receptors like insulin. The binding affinities of visfatin are similar to insulin. However, it does not show any competition with insulin referring to variations in the receptor sites. Visfatin is seen in lower levels in comparison to insulin. Visfatin levels in plasma correlate with percent body fat and is observed to increase in cases of obesity. Visfatin and leptin have highly conserved amino acids and do not show any homology to any other protein. Neurons express the receptors for both leptin and visfatin. This occurs in the arcuate nucleus present in the hypothalamus. This is the area of the brain which plays a big role in energy metabolism and its regulation.

Functions of visfatin are still not very clear, but this adipocytokine which is similar to leptin has shown some role in body weight regulation. PBEF gene encodes 491 amino acid residue polypeptide which later loses 26 N-terminal residues and secreted as 465 amino acid residue, as visfatin. This is known for its participation in NAD synthesis. Visfatin plays a role in body weight regulation through afferent signal reflection of excess body fat. Visfatin also enhances phagocytosis, production of IL-6 and CCL2 in the umbilical cord and upregulation of VEGF expression. Visfatin expression is regulated by conditions like inflammation, hyperglycemia and hypoxia which leads to upregulation and presence of statins, insulin and somatostatin which leads to downregulation.