glucose

glucose, one of a group of carbohydrates known as simple sugars (monosaccharides). Glucose (from Greek glykys; “sweet”) has the molecular formula C₆H₁₂O₆. It is found in fruits and honey and is the major free sugar circulating in the blood of higher animals.

Glucose is the source of energy in cell function. The regulation of its metabolism is of great importance and is relevant in various metabolic processes, examples being fermentation and gluconeogenesis. Molecules of starch, the major energy-reserve carbohydrate of plants, consist of thousands of linear glucose units. Another major compound composed of glucose is cellulose, which is also linear. Dextrose is the molecule d-glucose.

The maintenance of the glucose content of vertebrate blood requires glucose 6-phosphate to be converted to glucose. This process occurs in the kidney, in the lining of the intestine, and most importantly in the liver. The liver stores excess glucose as glycogen, a reserve carbohydrate, and releases it when blood glucose levels drop, thereby preventing hypoglycemia. In addition, the liver can produce glucose from non-carbohydrate sources through gluconeogenesis, which helps ensure a steady supply of glucose for the body.

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