The reaction of oxygen and glucose produces energy and carbon dioxide. Carbohydrate and water are also both by-products of the reaction. Some energy released is in the form of heat which maintains human body temperature.
Glucose reacts with oxygen during a process called cellular respiration, which takes place inside the mitochondria of a cell. Cellular respiration has four stages: glycolysis, the preparatory reaction, the citric acid cycle and the electron transport chain. Although glucose and oxygen react at the cell level, glucose does not dissolve into ions in water. It only reacts when hydrogen bonding occurs between the glucose and water molecules. Glucose is relatively unreactive and does not react with oxygen under room temperature.