Insulin

Diabetes manifests in two types. Type I diabetes is also called childhood onset because it begins in early childhood. Adult onset diabetes or Type II affects adults.

Glucose is a source of energy to the muscles of the body. Normally, the glucose content of blood is determined by the demands made by the muscles; the secretion of insulin, which lowers blood glucose; the secretion of glucagon, also manufactured and secreted in the pancreas, which raises blood glucose; extraction by the liver of glucose from the blood to be converted to glycogen and stored; and other hormones secreted by the adrenal and pituitary glands. The secretion of glucagon in the pancreas is a function of the alpha cells of the islets of Langerhans, and the secretion of insulin is the function of the beta cells of the same islets.

If the beta cells fail to function properly or are genetically insufficient in number to provide the needed hormone, diabetes can result. Also, in adults, the damage to, or failure of the cells resulting in lowered insulin secretion can lead to diabetes mellitus.

No cure has been found for diabetes; that is, no way has been found to restore full function to the beta cells in the islets of Langerhans. Individuals who have diabetes must take insulin by injection or take pills that control carbohydrate metabolism.

The insulin used by diabetics used to be extracted from porcine (pig) and bovine (cattle) pancreas. However, with the genetic revolution, genetic engineering has allowed bacteria to be transformed to produce human insulin protein, which is purified from large industrial cultures. Thus, human insulin is obtained from bacteria that have human genes inserted into them. Human insulin technology has advanced to produce new, more effective forms of insulin. One of the problems with insulin therapy is that diabetic patients must inject themselves with insulin regularly—an unpleasant process for many people. The development of Humulin-L, Humulin-N, Humulin-R, and Humulin-U have allowed some patients to reduce the frequency of shots required. These new forms of human insulin (from which the name Humulin comes) have effects that last longer than ordinary insulin, making fewer injections possible. As a result, more diabetes patients are likely to stick to their insulin therapy.