GCG and type 2 diabetes mellitus: Furthermore, from the triumvirate theory, Defronzo (2009) suggested there is much more to the pathogenesis of T2DM, suggesting five additional elements that make substantial contributions to the development and evolution of the disease: (1) alterations in the enteroendocrine physiology, (2) increased lipolysis in fat cells, (3) increased glucagon secretion, (4) increased renal reabsorption of glucose, and finally (5) CNS insulin resistance with appetite dysregulation [101].