Insulin decreases blood glucose concentration. It increases cell permeability to monosaccharides, amino acids and fatty acids. It accelerates glycolysis, the pentose phosphate cycle, and glycogen synthesis in liver. Heterodimer of a B chain and an A chain linked by two disulfide bonds. Due to a substitution of the Arg in position 31 by an Ile, this insulin B chain is longer than most other B chains and is processed differently. Belongs to the insulin family.