CRTC2 and type 2 diabetes mellitus: Interestingly, these genes, such as BHLHE41 [51,52], CRTC2 [53,54], CRY2 [55,56] and TEF [57], are involved in regulating circadian rhythms and various biological processes, including transcription regulation, signal transduction, and metabolic pathways, which are critical in the pathophysiology of T2DM.