Insulin is an 5,8 kDa peptide hormone composed of 51 amino acids coded by the insulin (INS) gene at 11p15.5. Insulin is the main anabolic hormone of the body. It is only produced in beta cells of the pancreatic islets and its production level is dependent on the blood glucose level. Pancreatic beta cells are sensing the serum glucose levels and secrete insulin in response to a high serum level of glucose, while low glucose levels inhibit insulin secretion. Insulin regulates the metabolism of carbohydrates and fat by promoting the absorption of glucose from the blood into liver, fat and skeletal muscle cells where it is converted into glycogen and/or triglycerides. Insulin also regulates protein synthesis in various tissues. Low serum insulin levels have the opposite effect and result in catabolism, especially of body fat. Decreased or absent insulin results in diabetes mellitus, a condition of high blood glucose (hyperglycaemia).