SLC2A4 and diabetes mellitus: Accordingly, immunoblotting of muscle and fat tissue showed a 2- to 3-fold increase of Glut4 in the insulin hypersensitive Hmga1-knockout mice compared with controls (Figure 7), clearly indicating that an inverse correlation between RBP4 and Glut4 indeed exists in vivo, in this animal model of diabetes, in which reduced RBP4 may contribute to the maintenance of glucose homeostasis by increasing insulin signaling and peripheral insulin sensitivity.