The article aims to outline the historical development of treatment of diabetes in Czechoslovakia. Information has been obtained mainly from two Czech journals, Časopis lékařů českých (The Journal of Czech Physicians, published since 1862) and Praktický lékař (The General Practitioner, published since 1921). Until the discovery of insulin, the treatment of diabetes was based on the use of different diets and a great benefit was obtained by spa treatment. In 1923, imported insulin appeared on the market in Czechoslovakia; insulin injections or substances from which insulin was prepared. In the years 1923-1945, insulin was produced by five companies, then insulin and oral antidiabetics were manufactured just by one firm Léčiva (Pharmaceuticals).