GIP and type 2 diabetes mellitus: Taking into account the considerable reduction in incretin effect (i.e., the secretion of insulin in response to oral glucose ingestion mediated by GLP-1 and glucose-dependent insulinotropic peptide—GIP) in patients with T2DM and the significant anti-hyperglycemic action, GLP-1 RAs are strongly recommended in the management of patients with T2DM [13].