GIP and diabetes mellitus: We have already demonstrated that reduced RS, reflecting the β cell ability to rapidly respond to changes in glucose levels during early insulin release, predicted diabetes appearance in a cohort of nondiabetic subjects undergoing acute β cell mass loss by pancreatoduodenectomy (15); in the present study, we observed a positive association between RS and GIP/GLP-1 SR, possibly expressing a predictive role of disproportionate incretin secretion on impaired first-phase insulin secretion.