INS and type 2 diabetes mellitus: There is an increasing body of scientific evidence supporting the role of vitamin D in pancreatic beta cell function, systematic inflammation related to T2D, and insulin sensitivity [120], and numerous studies confirmed that elevated levels of vitamin D in the bloodstream are linked to a reduced risk of developing T2D [121,122,123], indicating that it may also have a role in the occurrence of T2D complications [43,124].