Hemopoietic stem cells (HSCs) are commonly used for curing malignant and nonmalignant hematopoiesis disorders. In recent years, HSC potential giving rise to multilineage progeny has been reported. This issue, together with their availability and number, has made them ideal candidates for beta-cell replacement in diabetic patients. HSC capacity to differentiate to insulin-producing cells has been at the center of debate for the past 5 years and it now seems that their role could more likely be that of helper cells able to facilitate survival or stimulate proliferation of endogenous beta cells. In addition, clinical studies are ongoing about the possible use of HSCs to stop autoimmune destruction at the onset of diabetes or to induce tolerance through microchimerism in pancreatic islet transplantation.