Adipocyte-originated hormonal factors, playing a role of signaling particles, are widely engaged in energy control, feeding behavior and general glucose or lipid metabolism. One of them resistin has been suspected to initiate or develop insulin resistance and diabetes. From the moment of discovery of resistin, during last 13 years, numerous investigations put some light on a potential role of this hormone in mammals. In this review knowledge on resistin, including its structure, physiological role related to obesity and diabetes, as well as, gene sequence and phenotypic effects of the identified polymorphisms in human and domestic mammals is discussed.