In obesity and T2D, insulin resistance has been linked mainly to defects in the signalling pathway of phosphatidylinositol 3-kinase and protein kinase B (PI3K/Akt), particularly to the Akt2 isoform (Cusi et al., 2000; Krook et al., 2000). This evidence concerns the gene AKT2 and obesity due to melanocortin 4 receptor deficiency.