INS and Insulin resistance: Nod2−/− HFD mice had significantly higher levels of serum insulin than WT HFD, Nod2−/− LFD, and WT LFD mice (Fig. 1i), and exhibited a mild but significantly reduced response to exogenous insulin compared with WT HFD mice 120 min after an insulin challenge (Fig. 1j), which indicates the development of insulin resistance and suggests that partial compensation may be achieved by increased insulin production.