Diaconescu won her first international medals in 1957, winning gold at the Balkan Games in Athens with a throw of 52.14 m and placing second behind Inese Jaunzeme at the UIE World Student Games in Moscow with 50.06 m. Jan Popper, a Czechoslovakian sports statistician, ranked her second in the world that year, behind only Dana Zátopková and ahead of the previous year's number one, Jaunzeme. In 1958 Diaconescu placed seventh at the European Championships, but was not ranked in the world's top ten. In 1959 she placed third behind Elvīra Ozoliņa and Urszula Figwer at the first Summer Universiade in Turin. She competed in the 1960 Summer Olympics in Rome, qualifying for the final but only placing tenth.