PER1 and type 2 diabetes mellitus: The relevance of hepatic expression patterns of these genes to T2D remission in humans is supported by the identification of altered regulation of pathways related to the circadian clock in islets from individuals with early-stage T2D, and potentially T2D-causing mechanisms, characterized mainly by increased expression of Clock and decreased expression of Per1, Per2, Ciart, Cry2 and Usp258.