MTNR1A and type 2 diabetes mellitus: Notably, MTNR1A gene polymorphism has been closely linked to various diseases, including oral cancer, polycystic ovary syndrome, type 2 diabetes, and Alzheimer’s disease (Lin et al., 2015; Sulkava et al., 2018; Yi et al., 2020; Amin and Gragnoli, 2023).