Considering evidence that circulating LCN2 levels are associated with hyperglycemia, insulin resistance, and metabolic syndrome based on in vitro (Yan et al., 2007; Chan et al., 2016), in vivo (Wang et al., 2007; Guo et al., 2010), and clinical studies (Cakal et al., 2011), it is speculated that LCN2 may be involved in the regulation of insulin sensitivity in the brain, although the relationship between LCN2 expression and insulin resistance in the brain has not been investigated. The gene discussed is LCN2; the disease is Insulin resistance.