To pursue this aim, we calculated the GIP/GLP-1 secretion ratio (SR) and explored its role as a possible marker of unbalanced incretin secretion in T2D as well as its association with impaired β cell function and glucose intolerance in an attempt to enhance the understanding of the pathophysiological changes in incretin dynamics across deterioration of glucose tolerance as well as the impaired incretin response observed in T2D. This evidence concerns the gene GIP and type 2 diabetes mellitus.