INS and diabetes mellitus: One of the most prevalent systemic diseases worldwide is diabetes mellitus (DM), a chronic metabolic disorder composed of two subtypes: Type 1 DM involves 5-10% of diabetic patients and is an autoimmune disorder related to the destruction of pancreatic β-cells and the consequent deficit in insulin production; Type 2 DM, involves 90-95% of diabetic patients and is a multifactorial disease caused by environmental factors (e.g. obesity and sedentary lifestyle, corticosteroids intake) which lead to peripheral or cellular insulin resistance in genetically predisposed cases (4).