Description:Diurnal oscillation in glucose metabolism is strictly regulated by various factors, circadian rhythm. We used a isotopologue tracing method to characterize the diurnal oscillation in glucose metabolite isotopes in Drosophila sp. Specifically, the circadian rhythm and sleep was investigated. Wild type, hyperactive fumin mutant and Per mutant flies with loss in curcadian rhythm were injected with uniformly labeled 13C glucose . Different isotopologues of glucose metabolites were measured using UPLC-MS/MS to assess their circadian rhythm, or loss thereoff, in the downstream glucose metabolites.