In 2016 season, Diachenko started her season competing at the 2016 L.A Lights followed by competition at the 2016 Valentine Cup in Tartu, Estonia. She then competed at the Junior World Cup events in Pesaro, Guadalajara, Budapest, Sofia. Diachenko repeated as the Ukrainian Junior National champion. At the 2016 European Junior Championships Diachenko finished 6th with Team Ukraine; she qualified to 3 individual finals finishing 7th in hoop, 6th in clubs and 8th in ball. On September 9–11, Diachenko together with seniors Ganna Rizatdinova and Viktoria Mazur represented team Deriugina school at the annual 2016 Aeon Cup in Tokyo, where they won the team bronze and with Diachenko finishing 4th in the junior individual all-around.