On the occasion of the centennial of insulin therapy (1922–2022), II-Organotherapy of diabetes mellitus (1906–1923): Acomatol. Pancreina. Insulin.

Aims The general objective has been the historiographical investigation of the organotherapy of diabetes mellitus between 1906 and 1923 in its scientific, social and political dimensions, with special emphasis on the most relevant contributions of researchers and institutions and on the controversies generated on the priority of the "discovery" of antidiabetic hormone. Methods We have analyzed the experimental procedures and determination of biological parameters used by researchers during the investigated period (1906–1923): pancreatic ablation techniques, induction of acinar atrophy with preservation of pancreatic islets, preparation of pancreatic extracts (PE) with antidiabetic activity, clinical chemistry procedures (glycemia, glycosuria, ketonemia, ketonuria, etc.). The field investigation has included on-site and online visits to cities, towns, buildings, laboratories, universities, museums and research centers where the reported events took place, obtaining documents, photographic images, audiovisual recordings, as well as personal interviews complementary to the documentation consulted (primary sources, critical bibliography, reference works). The documentary archival sources have been classified according to theme, including those consulted in situ with those extracted online and digitized copies received mainly by email. Among the many archives contacted, those listed below have been most useful and have been consulted on site and on repeated visits: National Library of Medicine-Historical Archives (Bethesda, MD, USA); Archives, University of Toronto and Thomas Fisher Rare Books Library (Toronto, Ontario, Canada); Francis A. County Library of Medicine, Harvard University (Boston, Mass, USA); Zentralbibliothek der Humboldt-Universität (Berlin, DE), Geheimarchiv des Preuβischen Staates (Berlin, DE); Landesamt für Bürger—und Ordnungsangelegenheiten (LABO) (Berlin, DE); Arhivele Academiei Române şi Universitǎții Carol Davila (Bucharest, RO). Main results and conclusions A) The European researchers Zülzer (Z Exp Path Ther 23:307–318, 1908) and Paulescu (CR Seances Soc Biol Fil 85:558, 1921) meet the requirements of the priority rule in the discovery of the antidiabetic hormone. B) Factors of socioeconomic and political nature related with the First World War and the inter-war period delayed the process of purification of the antidiabetic hormone in Europe. C) The Canadian scientist J. Collip, University of Alberta, temporarily assimilated to the University of Toronto, and the American chemist and researcher G. Walden, with the expert collaboration of Eli Lilly & Co., were the main authors of the purification process of the antidiabetic hormone. D) The scientific evidence, reflected in the heuristics of this research, allows to assert that the basic investigation carried out by the Department of Physiology of the University of Toronto, directed by the Scottish J. Macleod, in conjunction with the clinical research undertaken by the Department of Medicine of the University of Toronto (W. Campbell, A. Fletcher, D. Graham) made it possible in record time the successful treatment of patients with what was until then a deadly disease.