INS and type 2 diabetes mellitus: Islet β cells shift from a compensatory increase to reduced function and decreased β cell mass.27 In the early stage of T2D, impaired insulin synthesis and secretion plays a major role, with the stimuli reducing glucose-stimulated insulin secretion (GSIS), the basic function of β cells.74 Progressively, chronic exposure to high glucose and lipids affects the survival of islet β cells, and the loss of mass gradually exacerbates with the prolongation of T2D and becomes the main factor involved in insufficient secretion of insulin.