Plasma Glucose

Glucose is a monosaccharide sugar that our bodies obtain from food and use as our principal energy source. The basic molecular form of glucose is C6H12O6. Glucose enters our body in several different forms, such as fructose and galactose, which are monosaccharides and isomers of glucose. These monosaccharides can combine to form disaccharides such as lactose and sucrose. Larger polymers of glucose are the polysaccharide forms of glucose which include starch, glycogen, and cellulose. Our bodies must break down complex sugars into glucose, fructose, and galactose for absorption and metabolism.

The glucose concentration in the blood is regulated by the complex interplay of multiple pathways modulated by several hormones. Glycogenesis is the conversion of glucose to glycogen. The reverse process involves the breakdown of glycogen into glucose and other intermediate products, termed glycogenolysis. The formation of glucose from non-carbohydrate sources, such as amino acids, glycerol, or lactate, is gluconeogenesis. The conversion of glucose or other hexoses into lactate or pyruvate is called glycolysis. Further oxidation to carbon dioxide and water occurs through the Krebs (citric acid) cycle and the mitochondrial electron transport chain coupled to oxidative phosphorylation, generating energy in the form of adenosine triphosphate (ATP).