Epidemiology of type 2 diabetes mellitus

Diabetes mellitus represents a group of metabolic disorders characterized by hyperglycaemia, which may or may not be associated with symptoms. The chronic hyperglycaemia of diabetes results from defects in insulin secretion, insulin action, or both, and is associated with long-term organ damage, particularly in the eyes, kidneys, nerves, heart, and blood vessels. Patients with type 2 diabetes have a higher prevalence of obesity (particularly abdominal obesity), hypertension, and lipid disorders, as well as an increased risk of macrovascular disease in coronary, peripheral, and cerebral arterial circulations, than people without diabetes. Microvascular complications of diabetes include retinopathy, which can lead to loss of vision, nephropathy (leading to renal failure), neuropathy (with an increased risk of foot ulcers, amputations, and foot deformations), and autonomic neuropathy, causing cardiovascular, gastrointestinal, genitourinary, and sexual dysfunction. Diabetes may have a serious emotional and social impact on affected individuals and their families, and has major economic implications for society as a whole in both developed and developing countries.