Glucose is one of major nutrients and its catabolism provides energy and/or building bricks for cell proliferation. Glucose deficiency results in cell death. However, the underlying mechanism still remains elusive. By using our recently developed method to monitor real-time cellular apoptosis and necrosis, we show that glucose deprivation can directly elicit necrosis, which is promoted by mitochondrial impairment, depending on mitochondrial adenosine triphosphate (ATP) generation instead of ATP depletion. We demonstrate that glucose metabolism is the major source to produce protons. Glucose deficiency leads to lack of proton provision while mitochondrial electron transfer chain continues consuming protons to generate energy, which provokes a compensatory lysosomal proton efflux and resultant increased lysosomal pH. This lysosomal alkalinization can trigger apoptosis or necrosis depending on the extent of alkalinization. Taken together, our results build up a metabolic connection between glycolysis, mitochondrion, and lysosome, and reveal an essential role of glucose metabolism in maintaining proton homeostasis to support cell survival.