Glucose is a simple sugar that provides energy to living things. It has the chemical formula C6H12O6 and is known as D-glucose, dextrose, or grape sugar. Glucose is soluble in water, has a melting point of 146°C, and a density of 1.54 g/cm3. It exists as two isomers, D-glucose and L-glucose, with D-glucose being the form used by organisms. Glucose is produced from carbohydrates through digestion and is the main energy source for humans, animals, and plants. It fuels brain activity and treating low blood sugar.