[The role of inflammation in the development of insulin resistance in type 2 diabetes].

Insulin resistance observed in type 2 diabetes or obesity is closely associated with a state of low-grade inflammation. The gene expressions of numerous inflammatory mediators, such as proinflammatory cytokines, are increased in adipose tissues of human and animal models of obesity or type 2 diabetes. These inflammatory mediators inhibit insulin signaling with several mechanisms, such as serine-phosphorylation of IRS-1, the induction of SOCS3 and the activation of JNK or NFkappaB signaling in insulin-target tissues. They are mainly produced by the classically-activated macrophages, termed M1 macrophages, in obese adipose tissues. In contrast, alternatively-activated macrophages, termed M2 macrophages, are observed even in the non-obese adipose tissues. The activation of PPAR signaling is highly associated with the alternative activation of myeloid cells.