CLOCK and Hyperglycemia: In a seminal study assessing the impact of genetic perturbation of the clock gene, Turek and colleagues found increased body weight and greatly attenuated diurnal feeding rhythms and hyperphagia, together with hyperleptinemia, hyperlipidemia, hepatic steatosis, hyperglycemia and insulin resistance in homozygous Clock mutant mice fed a HFD, pointing to an important role of the circadian clock in the control of mammalian energy balance [44].