Spontaneous hypoglycemia in non-diabetic patients poses a diagnostic challenge. Hypoglycemia in malignancy has several etiologies; an extremely rare mechanism is the Warburg effect causing excess lactate production and avid glucose consumption. We describe the clinical course of a 52-year-old man admitted for chest wall mass and severe but asymptomatic hypoglycemia. Laboratory work-up was obtained for insulin vs non-insulin mediated hypoglycemia, and biopsy of the chest wall mass and 18F-FDG-PET/CT scan were performed. D10 infusion and intravenous/oral steroids started for severe hypoglycemia. Chemotherapy initiated after biopsy, and BG and lactate levels followed with clinical response in tumor size and changes in PET/CT. Investigations were significant for venous BG in 40s [Ademolus Classification of Hypoglycemia grade 2 hypoglycemia], plasma insulin <2 µU/mL (2-20), c-peptide 0.2 ng/mL (0.8-6.0), IGF-II 113 ng/mL (333-967), serum lactate 16 mmol/L (0.5-2) and albumin of 2.3 g/dL (3.4-5.4). Biopsy showed diffuse large B-cell lymphoma, and PET revealed highly FDG-avid disease in chest, abdomen, pelvis but no FDG uptake seen in brain. Hypoglycemia and lactic acidosis improved remarkably after chemotherapy. PET/CT at 4 weeks showed complete metabolic response with reappearance of physiological FDG uptake in brain. Non-insulin mediated hypoglycemia was likely due to the combination of profound malnutrition and rapid glucose utilization by cancer cells. Patient presented with exaggerated Warburg effect (hyper-Warburgism), evident by extreme glucose consumption, severe lactic acidosis, and large tumor burden on PET/CT. Absence of cognitive symptoms was probably due to utilization of lactate by brain. Chemotherapy corrected these abnormalities rapidly and must be instituted timely.