Diabetes mellitus type 2
From Free net encyclopedia
Template:DiseaseDisorder infobox
- See diabetes mellitus for further general information on diabetes.
Diabetes mellitus type 2 (formerly called diabetes mellitus type II, non-insulin-dependent diabetes, NIDDM or adult-onset diabetes) is a long-term metabolic disorder that is primarily characterized by insulin resistance, relative insulin deficiency, and hyperglycemia. Unlike Type 1 diabetes, there is little tendency toward ketoacidosis in Type 2 diabetics. Complex and multifactorial metabolic changes lead to damage and function impairment of many organs, most importantly the cardiovascular system. This leads to substantially increased morbidity and mortality in both Type 1 and Type 2 patients, but the two have quite different origins and treatments despite the similarity in complications which often confuse even diabetics.
Contents |
Pathophysiology
Genetic factors, usually polygenic, form disease background in a prevailing number of patients. Environmental factors like obesity, lack of exercise and sedentary lifestyle sometimes lead to insulin resistance. Insulin resistance means that body cells do not respond appropriately when insulin is present.
Other important contributing factors:
- increased hepatic glucose production (eg, from protein degradation)
- decreased insulin-mediated glucose transport in muscle and adipose tissues (receptor and post-receptor defects)
- impaired beta-cell function - loss of early phase of insulin release in response to hyperglycemic stimuli
This is a more complex problem than type 1, but is sometimes easier to treat especially in the initial years, when insulin is often still produced. Type 2 may go unnoticed for years in a patient before diagnosis, since the symptoms are typically milder (no ketoacidosis) and can be sporadic. However, severe complications can result from unnoticed type 2 diabetes, including renal failure, blindness, wounds that fail to heal, and coronary artery disease. The onset of the disease is most common in middle age and later life.
Diabetes mellitus type 2 is presently of unknown etiology or cause. Diabetes mellitus that has a known etiology, such as secondary to other diseases, known gene defects, or effects of drugs, is more appropriately called secondary diabetes mellitus. Examples include diabetes mellitus caused by hemochromatosis, pancreatic insufficiency, or certain types of medications (e.g. long-term steroid use).
About 90-95% of all North American cases of diabetes are type 2, and about 20% of the population over the age of 65 has diabetes mellitus type 2. The fraction of type 2 diabetics in other parts of the world varies substantially, almost certainly for environmental and lifestyle reasons. There is also a strong inheritable genetic connection in type 2 diabetes: having relatives (especially first degree) with type 2 is a considerable risk factor for developing type 2 diabetes. The majority of patients with type 2 diabetes mellitus are obese - chronic obesity leads to increased insulin resistance that can develop into diabetes, most likely because adipose tissue is a (recently identified) source of chemical signals (hormones and cytokines). Other research shows that type 2 diabetes causes obesity.1
Diabetes mellitus type 2 is often associated with obesity and hypertension and elevated cholesterol (combined hyperlipidemia), and with the condition Metabolic syndrome (also known as Syndrome X). It is also associated with acromegaly, Cushing's syndrome and a number of other endocrinological disorders.
Treatment
Diabetes mellitus type 2 is a chronic, progressive disease that cannot be cured. It implicates two main goals of treatment of the disease:
- reduction of mortality and concomitant morbidity (diabetic complications)
- preservation of quality of life
The first goal can be achieved through stringent glycemic control that has been corroborated by numerous wide scale clinical trials. The second goal requires care that is provided by teams of diabetic health workers and patient education is the crucial point in the process.
Type 2 is initially treated by changes in diet and through weight loss in obese patients. This can restore insulin sensitivity, even when the weight lost is modest e.g. around 5 kg (10 to 15 lb). The next step, if necessary, is treatment with oral antidiabetic drugs:
- the sulphonylureas
- metformin
- thiazolidinediones
- α-glucosidase inhibitors
- natiglinide, repaglinide and their analogues
- exenatide
When these have failed, insulin therapy may be necessary, usually as an adjunct to oral therapy, to maintain normal glucose levels. The term non-insulin-dependent diabetes is an outdated term. The classification or type of diabetes is determined by the underlying cause of the diabetes, not the type of therapy that is used to treat the diabetes. Many patients with diabetes type 2 will progress to require insulin for control of blood glucose levels, but these patients are still classified as having type 2 diabetes.
See also
References
- S Camastra, E Bonora, S DelPrato, K Rett, M Weck, E Ferrannini. Effect of obesity and insulin resistance on resting and glucose-induced thermogenesis in man. International Journal of Obesity, 1999, Vol 23, Iss 12, pp 1307-1313. PMID 10643689fr:Diabète de type 2