[Etiopathogenesis and pathophysiology of type 2 diabetes].

Etiopathogenesis of type 2 diabetes is complex and still partially unknown. Its etiology is determined by the interaction of genetic and environmental factors. The genetic contribution is important, but has a polygenic origin. Obesity, especially when fat mass is preferably located in the abdomen, is the main predisposing factor for type 2 diabetes, and almost 80% of diabetic patients are overweight or obese. The diabetogenic effect of obesity is due to the capacity of excessive fat mass to induce or aggravate insulin resistance. Increasing lack of physical activity is also a contributing factor as it increases insulin resistance. As far as pathophysiology is concerned, the development of type 2 diabetes results from the coexistence of abnormalities of insulin secretion and insulin action. Insulin secretory dysfunction, whose underlying mechanism remains poorly understood, is characterized by a relative defect in circulating insulin levels of variable severity. Resistance to insulin action is located in the liver (increased hepatic glucose production), in the skeletal muscle (decreased muscular glucose uptake) and in the adipose tissue (exaggerated lipolysis with elevated plasma free fatty acids). Changes in life-style habits (weight reduction, regular physical activity) are able to prevent or delay the development of type 2 diabetes.