Uridine is a pyrimidine nucleoside found in plasma and cerebrospinal fluid, with higher concentrations than other nucleosides. It plays a critical role in various biological processes, including nucleic acid synthesis, glycogen synthesis, and O-GlcNAcylation, which regulates protein function. Uridine also influences body temperature, circadian rhythms, and metabolic gene expression. Abnormal uridine levels are associated with metabolic disorders such as diabetes, obesity, and neurodegenerative diseases. While uridine may have short-term benefits in glucose and lipid metabolism, long-term dysregulation can lead to metabolic damage. Uridine's role in protein modification, particularly through O-GlcNAcylation, is linked to diseases like cancer, Alzheimer's disease, and diabetes. Uridine promotes tumor growth by enhancing cell proliferation and survival, while it may also have neuroprotective effects by reducing Tau phosphorylation and amyloid accumulation. Uridine supplementation has shown potential in treating diabetic neuropathy by improving nerve function and reducing oxidative stress. In obesity, uridine metabolism is linked to energy intake, lipid storage, and breakdown, with both short-term and long-term effects on metabolic health. Uridine also influences glucose homeostasis, with short-term supplementation improving glucose tolerance but long-term use potentially causing insulin resistance. Uridine's impact on vascular complications of diabetes is mediated through O-GlcNAcylation of vascular proteins, which can impair endothelial function and increase oxidative stress. Overall, uridine plays a complex role in metabolic processes, and its regulation is essential for maintaining metabolic homeostasis. Further research is needed to fully understand its therapeutic potential in metabolic diseases.Uridine is a pyrimidine nucleoside found in plasma and cerebrospinal fluid, with higher concentrations than other nucleosides. It plays a critical role in various biological processes, including nucleic acid synthesis, glycogen synthesis, and O-GlcNAcylation, which regulates protein function. Uridine also influences body temperature, circadian rhythms, and metabolic gene expression. Abnormal uridine levels are associated with metabolic disorders such as diabetes, obesity, and neurodegenerative diseases. While uridine may have short-term benefits in glucose and lipid metabolism, long-term dysregulation can lead to metabolic damage. Uridine's role in protein modification, particularly through O-GlcNAcylation, is linked to diseases like cancer, Alzheimer's disease, and diabetes. Uridine promotes tumor growth by enhancing cell proliferation and survival, while it may also have neuroprotective effects by reducing Tau phosphorylation and amyloid accumulation. Uridine supplementation has shown potential in treating diabetic neuropathy by improving nerve function and reducing oxidative stress. In obesity, uridine metabolism is linked to energy intake, lipid storage, and breakdown, with both short-term and long-term effects on metabolic health. Uridine also influences glucose homeostasis, with short-term supplementation improving glucose tolerance but long-term use potentially causing insulin resistance. Uridine's impact on vascular complications of diabetes is mediated through O-GlcNAcylation of vascular proteins, which can impair endothelial function and increase oxidative stress. Overall, uridine plays a complex role in metabolic processes, and its regulation is essential for maintaining metabolic homeostasis. Further research is needed to fully understand its therapeutic potential in metabolic diseases.