SDC1 and metabolic syndrome: Syndecans (SDCs) are a family of type-I transmembrane glycoproteins that function as heparan sulphate proteoglycans, with SDC4 being widely expressed in the body [43] Crocco et al. reported that genetic variants in SDC4 are associated with components of metabolic syndrome in humans, and that Sdc4 knockout in mice affects fat accumulation and insulin sensitivity [44].