Pancreatic Islet Transplantation and Regeneration for Diabetes mellitus Treatment The incidence of diabetes mellitus due to different causes (heredity, unhealthy food, sedentary life style, etc.) is increasing both in Latvia and worldwide every year. In almost all cases insulin therapy must be administered. However, the latest modern technologies promote the development of new and alternative treatments of diabetes mellitus. One of them, the procedure of islet transplantation is comparatively simple and relatively non-invasive in contrast to whole pancreas transplantation. It is considered as a perspective strategy in the treatment of patients with type 1 diabetes, when the insulin-producing beta cells have been destroyed and blood glucose level is above the normal range (hyperglycaemia). Successful outcome of clinical islet transplantation has been shown in several islet transplantation centres in Europe and elsewhere, particularly in the last seven years, using corticoid-free immunosuppression regimen. Islets are isolated by a collagenase-based digestion of donor pancreas with a "Ricordi" chamber, followed by a purification step in a Ficoll-based continuous density gradient. This review discusses the islet transplantation procedure and deals with the methods of islet isolation. Importance of islet preparations and engraftment quality, as well as clinical outcome and its indications also are described. The present status of islet regeneration including beta cells neogenesis and regeneration therapy strategies also are presented. The experience of Latvian scientists in islet transplantation procedure is briefly described.