Furthermore, while the concern of increased proliferation in β-cell is the worry of naive phenotype, both harmine + TGFβ and harmine + GLP-1 analog treatment of normal and T2DM human islets resulted in an increased expression of key β-cell markers including PDX1, NKX6.1, MAFA, and MAFB [66,97]. Here, GCG is linked to type 2 diabetes mellitus.