A large number of studies demonstrated the negative associations between circulating OCN level and fasting blood glucose level, fasting insulin level, insulin resistance and fat mass, and positive associations with insulin secretion, serum adiponectin level and fat-free mass in normal subjects or in patients with type 1 or type 2 diabetes, gestational diabetes, metabolic syndrome, and polycystic ovarian syndrome [17–21]. This evidence concerns the gene INS and metabolic syndrome.