• High fasting blood glucose (≥126 mg/dL) is an independent adverse prognostic factor in pancreatic cancer patients (HR=1.41, P=0.015).
• Only 19.6% of pancreatic cancer patients have normal fasting glucose, indicating widespread glucose dysregulation.
• In KRAS-mutated pancreatic cancer cells deprived of glutamine, glucose-derived carbons are incorporated into glutamate and related metabolites, suggesting glucose as a potential alternative source of glutamate.
• Isotope tracing revealed that glucose contributes to glycosylation, collagen/stroma, cell division, and ROS-related pathways under glutamine deprivation, highlighting metabolic plasticity.