Apoptosis, also known as programmed cell death,is a normal process contributing to tissue tumor during development and in the adult.During development apoptosis is involved in tissue homeostasis and eliminating nonfunctional,superfluous or harmful cells.It is an active process controlled by some gene and factors such as caspases, bcl-2, Fas/FasL and NO.Type 1 diabetes mellitus is regarded as a chronic autoimmune disease resulting from progressive destruction of insulin-producing β-cells in the pancreas.The relationship between apoptosis with its modulation and type 1 diabetes mellitus was reviwed.