Here, we found that the LRIG proteins function as regulators of lipid metabolism by regulating BMP signaling in several different biological systems, including adipocyte differentiation of mouse fibroblasts and in lipid accumulation in C. elegans; in addition, we found that human LRIG1 gene variants were associated with a decreased risk of type 2 diabetes, an increased BMI, and altered adipocyte morphology. This evidence concerns the gene LRIG1 and type 2 diabetes mellitus.