Diminished protein expression of IRβ, IRS2, PI3K85 PI3K110α, GLP‐1R, and GIPR was observed in T2D islets (Fig 5E), which was concomitant with the attenuation of insulin‐induced Akt phosphorylation and exendin‐4‐ or GIP‐induced CREB phosphorylation (Fig 5F–H). Here, CREB1 is linked to type 2 diabetes mellitus.