T2D is the most common form of the disease, and is associated with a late age of onset (generally after age 40 years). T2D can often be treated with diet, physical activity and / or oral hypoglycemic drugs. Insulin therapy may be used to improve metabolic control, but it is not necessary for survival. As a result, T2D may be relatively asymptomatic for many years before diagnosis.

T2D is considered to be a group of genetically heterogeneous metabolic diseases that ultimately result in glucose intolerance. Individuals with T2D generally have impaired insulin secretion and / or impaired insulin action. Both types of impairments ultimately lead to glucose intolerance and increased levels of circulating fatty acids.

T2D is likely caused by defects in multiple of genes, each of which appears to have a small effect. However, the interaction of these genes ultimately results in the onset of the disease. Thus, T2D is considered to be a polygenic disease. It is also considered to be multifactorial since environmental risk factors, particularly obesity and lack of physical activity, contribute to development of T2D.