The classical definition of a stem cell requires that it possesses two properties:Self-renewal: the ability to go through numerous cycles of cell division while maintaining the undifferentiated state.Potency: the capacity to differentiate into specialized cell types. In the strictest sense; to be able to give rise to any mature cell type, although multipotent or unipotent progenitor cells are sometimes referred to as stem cells.Types of stem cells:Stem cells could be classified into multiple categories; •According to their potential use in research and medicine: totipotent, pluripotent, multippotent, and unipotent.•Or according to their origin: Scientists primarily work with two kinds of stem cells from animals and adult stem cells, which have different functions and characteristics.•Or according to their destination.Umbilical cord blood is blood that remains in the placenta and in the attached umbilical cord after childbirth. Cord blood is obtained from the umbilical cord at the time of childbirth, after the cord has been detached from the newborn. Cord blood is collected because it contains stem cells, including hematopoietic cells, which can be used to treat hematopoietic and genetic disorders. Some placental blood may be returned to the neonatal circulation if the umbilical cord is not prematurely clamped.Umbilical cord blood is known as a rich source of hematopoietic stem cells, which makes it a valuable alternative to bone marrow transplantation in hematology and oncology. In addition to the HSC, a variety of different stem cell types have been identified within HUCB. Mesenchymal stem cells (MSC), endothelial stem cells (ESCs) and a not yet fully characterized population of multipotent cells can be found in the cord blood. Although these multipotent stem cells are very rare and may differentiate into a limited number of cell types, they may represent a promising tool for cell therapy. Diabetes is a disease that results from the body's inability to maintain consistent levels of glucose (the main energy source for cells) in the blood. In a healthy individual, blood glucose levels are kept within a certain range by insulin, a hormone that aids the uptake of glucose by cells. The release of insulin in response to blood glucose levels is coordinated by clusters of cells in the pancreas called islets; residing in these islets are the beta cells, the cells that actually produce and release insulin. Diabetes develops when there are too few functioning beta cells. Diabetes mellitus affects 18 million people in the U.S. alone (8.7% of the population); In rural Egypt, the prevalence was 4.9%, in urban Egypt, in areas of lower socioeconomic status, the prevalence of DM among those aged 20 years and over was 13.5%, compared to 20% in urban areas of higher socioeconomic status , and more than 190 million worldwide. The prevalence of diabetes has increased alarmingly in the past three decades and corresponding to global dietary and lifestyle trends, is projected to nearly double in the next ten years.In this study we aimed to Detect the feasibility of generating insulin-producing cells obtained from progenitor cells of cord blood, and their success in reversing the hyperglycaemia in diabetic rats. Our study confirmed that CB-MSCs are able to differentiate into islets that can secrete insulin in response to glucose in vitro and in vivo. The transplantation of culture-expanded, undifferentiated CB-MSCs in experimental diabetic mice reversed hyperglycemia. Thus, these cells offer another non-pancreatic, readily available, noninvasive, and inexhaustible source of allogeneic stem cells for cell replacement therapy in diabetes.