Identification of a biocompatible immunoprotective membrane to prevent graft rejection remained elusive until the development of microcapsules formulated in alginate high in guluronic acid. We report insulin independence in a type 1 diabetic patient after encapsulated islet transplantation. Encapsulated human islets were injected intraperitoneally in a diabetic patient with a functioning kidney graft. Insulin independence with tight glycaemic control was demonstrated 9 months after the procedure. These results warrant a trial of a high dose of encapsulated islets in early-onset diabetic patients.