Dear Editor,Gluconeogenesis is one of the major mechanisms to main tain hepatic glucose homeostasis and dysregulation of hepatic gluconeogenesis contributes to hyperglycemia in type 2 diabetes.Under fasted conditions,increases in circulating glucagon promote hepatic glucose production through activation of gluconeogenic pathway by HDAC5 and CREB coactivator CRTC2 (Lv et al.,2016;Lv et al.,2017;Qiu et al.,2017).The circadian clock coordinates behavior and metabolism into rhythms not only in the central hypothalamus but also in peripheral tissues (Marcheva et al.,2010;Vollmers et al.,2009).Transcription factor BMAL1 heterodimerizes with CLOCK to activate the expression of Per and Cry,which in tu suppress CLOCK/BMAL1 activity (Reppert & Weaver,2002).Although BMAL1 knockout mice show fasting hypoglycemia (Rudic et al.,2004),the detailed mechanism of BMAL1 regulation on hepatic gluconeogenesis has not been thoroughly understood.