Currently, the only possible way to cure patients with diabetes is transplantation of the pancreas or its cells, which is a very effective way to achieve and maintain long-term physiological control of blood glucose, but due to various risks (rejection) associated with surgical interventions, this method is rarely used. We experimentally developed an effective method for the surgical treatment of diabetes mellitus by free implantation of pancreatic cell cultures and introduced into clinical practice. We have proved for the first time that xenografts for patients with type 1 diabetes mellitus in 50% of cases reduce the need for insulin in the first year after surgery.