NOD2 and diabetes mellitus: Interestingly, when Nod2−/− NOD mice were housed with Nod2+/+ NOD mice, they lost the protection from diabetes, and this evidence confirmed that T1D susceptibility in Nod2−/− NOD mice is dependent on the alteration of gut microbiota, which modulated the frequency and function of IgA-secreting beta-cells and IL-10 promoting T-regulatory cells.