DIABETES MELLITUS: CLASSIFICATION, EPIDEMIOLOGY, PHYSIOPATHOLOGY, IMMUNOLOGY, RISK FACTORS, PREVENTION AND NUTRITION.

Diabetes mellitus is a group of metabolic disorders characterized by the presence of chronic hyperglycemia accompanied by greater or lesser impairment in the metabolism of carbohydrates, lipids and proteins. Symptoms of high blood sugar include frequent urination, increased thirst, and increased hunger. If left untreated, diabetes can lead on many complications: diabetic ketoacidosis, hyperosmolar, hyperglycemic state, cardiovascular disease, stroke, chronic kidney disease, foot ulcers, eyes damage, or death. Diabetes is due to either the pancreas not producing enough insulin, or the cells of the body not responding properly to the insulin produced. There are different types of diabetes mellitus. Type 1 diabetes is characterized by autoimmune destruction of insulin producing cells in the pancreas by CD4+ and CD8+ T cells and macrophages infiltrating the islets, usually leading to absolute insulin deficiency. Type 2 diabetes is due to a progressive insulin secretory defect on the background of insulin resistance. The two main physiopathological defects in type 2 diabetes are impaired insulin secretion through a dysfunction of the pancreatic β-cell, and impaired insulin action through insulin resistance. Gestational diabetes refers to first-onset glucose intolerance occurring during pregnancy. The pathophysiology of gestational diabetes mellitus and type 2 diabetes are similar; diabetes gestational could be a reflection of an early stage of type 2 diabetes occurring in the context of pregnancy. Prevention and treatment involve maintaining a healthy lifestyle, diet and nutrition, regular physical exercise, a normal body weight, avoiding use of tobacco and blood pressure control.