Diabetes mellitus (DM) is a life-long disease marked by elevated levels of sugar in the blood, currently affecting over 350 million people worldwide. There are 3 main types; type 1 diabetes, type 2diabetes and gestational diabetes. The two most common forms are type 1 diabetes (an autoimmune disease where the immune system destroys the insulin -producing cells of the pancreas) and type 2 diabetes (characterized by gradual resistance to the effects of insulin). Gestational diabetes is the third main form and only occurs in some women during pregnancy. If untreated, gestational diabetes can damage the health of the fetus and such risks include macrosomia (high birth weight), congenital cardiac and central nervous system anomalies, and skeletal muscle malformations. There are symptoms and warning signs and diagnostic tests for diabetic diseases. There is an increasing number of drugs available for treatment of diabetes. Diabetes mellitus can affect different tissues and organs or systems in the body such as central and peripheral nervous systems, eye, cardiovascular system, oral cavity, renal system, gastrointestinal system, genital system, skin and soft tissues, bone and foot.