diabetes

Disease that can be caused by reduced production of the hormone insulin, or a reduced response of the liver, muscle, and fat cells to insulin. This affects the body's ability to use and regulate sugars effectively. Diabetes mellitus is a disorder of the islets of Langerhans in the pancreas that prevents the production of insulin. Treatment is by strict dietary control and oral or injected insulin, depending on the type of diabetes.

Insulin increases glucose uptake from the blood into most body cells, except the brain and liver. In the liver, its effect is to reduce the production of glucose. Insulin works with other hormones to keep the concentration of glucose in the blood stable. A person with diabetes does not have this close regulation and may find that his or her glucose levels rise dangerously after a meal. Normally urine does not contain glucose, but when the blood glucose levels rise in a diabetic person, it appears in the urine. A person with diabetes may also be likely to have glucose levels that are too low at times.

There are two forms of diabetes: type 1, or insulin-dependent diabetes, which usually begins in childhood (early onset) and is an autoimmune condition; and type 2, or non-insulin-dependent diabetes, which occurs in later life (late onset). Without treatment, the patient may go blind, suffer from ulcers, lapse into diabetic coma, and die. Early-onset diabetes tends to be more severe than that developing in later years. There is also a strong link between late-onset diabetes and being seriously overweight (obese) – over 80% of sufferers are obese. Although the precise nature of the link between diabetes and obesity is not known, studies showed that in mice a hormone secreted by fat cells blocked the action of insulin.

Sugar accumulates first in the blood, then in the urine. The patient experiences thirst, weight loss, and increased frequency of urination and volume of urine, along with degenerative changes in the capillary system. Without treatment, the patient may go blind, ulcerate, lapse into diabetic coma, and die. Early-onset diabetes tends to be more severe than that developing in later years. Before the discovery of insulin by Frederick Banting and Charles Best, severe diabetics did not survive. Today, it is seldom fatal. Careful management of diabetes, including control of high blood pressure, can delay some of the serious complications associated with the condition, which include blindness, disease of the peripheral blood vessels, and kidney failure. A continuous infusion of insulin can be provided via a catheter implanted under the skin, which is linked to an electric pump. This more accurately mimics the body's natural secretion of insulin than injections or oral doses, and can provide better control of diabetes. It can, however, be very dangerous if the pump malfunctions.

Much rarer, diabetes insipidus is due to a deficiency of a hormone secreted by the pituitary gland to regulate the body's water balance. It is controlled by hormone therapy.

In 1989 it was estimated that 4% of the world's population had diabetes, and that there were 12 million sufferers in Canada and the USA. In 2006 there were about 230 million sufferers worldwide, and the number was expected to continue to rise, to reach 350 million by 2025.

Diabetes among people in their 30s in the USA increased by nearly 33% from 1990 to 1998, according to a study by the US government's Centers for Disease Control and Prevention (CDC). The study found that diabetes has become more common for all ages, races, and educational levels. An increase in levels of obesity and a lack of physical activity among many people were seen as major contributing factors.

In 2000 it was recommended that overweight children with two other risk factors (including family history, high blood pressure, and high cholesterol) should be tested for type 2 diabetes. This recommendation came in response to an emerging epidemic of this type of diabetes, which is strongly linked to obesity. In 2000 there were about 300,000 cases among US children, although it was almost unknown ten years previously.

Cell transplant treatment In the UK in 2005 a cell transplant technique was used for the first time to cure a patient with type 1 diabetes. Doctors at Kings College Hospital, London, transplanted insulating-generating cells from dead donors into the patient's pancreas. After the transplant, the patient no longer required insulin injections. This treatment heralded a major breakthrough in ending the insulin dependence of diabetes sufferers.