INS and type 2 diabetes mellitus: Although the primary cause of T2D has not yet been determined, mitochondrial dysfunction in the organs responsible for insulin secretion (pancreatic beta cells), in the target organs of insulin action (skeletal and cardiac muscle cells and liver cells), and in the target organs associated with the major complications of T2D (kidneys, retina, nerves, and vascular cells) may play an important role in the pathophysiology of the disease [29].