Chronic jet lag or shift work is deleterious to human metabolic health, in that such circadian desynchronization is associated with being overweight and the prevalence of altered glucose metabolism. Similar metabolic changes are observed with age, suggesting that chronic jet lag and accelerated cell aging are intimately related, but the association remains to be determined. We addressed whether jet lag induces metabolic and cell aging impairments in young grass rats (2-3 mo old), using control old grass rats (12-18 mo old) as an aging reference. Desynchronized young and control old subjects had impaired glucose tolerance (+60 and +280%) when compared with control young animals. Despite no significant variation in liver DNA damage, shorter telomeres were characterized, not only in old animal liver cells (-18%), but also at an intermediate level in desynchronized young rats (-9%). The same pattern was found for deacetylase sirtuin (SIRT)-1 (-57 and -29%), confirming that jet-lagged young rats have an intermediate aging profile. Our data indicate that an experimental circadian desynchronization in young animals is associated with a precocious aging profile based on 3 well-known markers, as well as a prediabetic phenotype. Such chronic jet lag-induced alterations observed in a diurnal species constitute proof of principle of the need to develop preventive treatments in jet-lagged persons and shift workers.