INS and type 2 diabetes mellitus: Two classes of antidiabetic drugs, namely exendin analogs or dipeptidyl peptidase IV (DPPIV) inhibitors, which inhibit the degradation and thus the metabolism of endogenous GLP-1, are now being used as a promising T2DM treatment because they have the ability to reduce hyperglycemia by concomitantly stimulating insulin secretion and maintaining β-cell mass [60].