Diabetes mellitus, usually referred to as diabetes, is a serious disorder characterized by an excess of the sugar glucose in the blood and tissues of the body. The word diabetes derives from the Greek word for siphon, referring to the copious urine excretion that accompanies this affliction. Diabetes is a disease in which the pancreatic hormone insulin is either not produced or not properly used by the body. Insulin is necessary to convert sugar, starches, and other foods into the energy needed for daily life; thus, diabetes is characterized as a chronic metabolic disorder with hyperglycemia (high blood sugar) and abnormal energy metabolism. See also: Diabetes; Energy metabolism; Glucose; Insulin
Globally, diabetes is one of the most prevalent noncommunicable diseases. It is currently the fourth or fifth leading cause of death in most developed countries and a fast-rising cause of mortality and morbidity in the developing world as well. The causes of diabetes are a combination of genetic, autoimmune, and environmental factors, and the disease has no cure at this time.
The two principle forms of diabetes mellitus are type 1 (insulin-dependent) diabetes and type 2 (non-insulin-dependent) diabetes. Type 1 diabetes affects 5–10% of all people diagnosed with this disease and is caused by the immune system’s destruction of the beta cells of the pancreas, resulting in an absolute deficiency of insulin. Type 2 diabetes is the predominant form, affecting 90–95% of all the people who have diabetes. It is caused by a combination of resistance to the actions of insulin compounded by an inability of insulin secretion to compensate for the increased requirement of this hormone. The incidence and prevalence of type 2 diabetes are on the rise as a result of the epidemic of obesity, sedentary lifestyles, and the increasing age of the population in both developed and developing countries. Previously, type 2 diabetes was also termed adult-onset diabetes because it mostly affected individuals older than 40 years of age. However, the term is no longer appropriate because of the increase of type 2 diabetes in children as young as 10 years of age. (Some pregnant women manifest a third condition, gestational diabetes, which alters their glucose physiology temporarily, but usually clears up after delivery.) See also: Epidemic of obesity; Hormone; Pancreas; Type 1 diabetes; Type 2 diabetes
In general, management of type 1 diabetes focuses on the critical administration of insulin, as well as on diet and exercise. For type 2 diabetes, administration of oral hypoglycemic agents (drugs that lower blood glucose) and alterations in diet and physical activity are the main forms of preventive treatment.