Tiformin (also known as γ-Guanidinobutyramide) is a butyramide derivate with antidiabetic activity. Tiformin was isolated for the first time from a medium containing arginine which had been transformed by washed cells of Streptomyces griseus. In preclinical models, oral administration of Tiformin depresses blood glucose in rats and rabbits. Tiformin given i.v. produced hyperglycemia and sometimes death of experimental animals. Tiformin is not significantly metabolized in the rat or dog.