The most studied member of this family, GLUT4, is responsible for insulin-stimulated uptake of glucose into fat and muscle tissues; GLUT4 exhibits regulated delivery to the cell surface in response to insulin, and dysregulation of this process has been shown to be a hallmark for insulin resistance and type-2 diabetes (Klip et al. 2019). This evidence concerns the gene SLC2A4 and type 2 diabetes mellitus.