Despite the presence of various approaches for controlling diabetes mellitus (DM), such as dietary adjustment (Asif, 2014) and hypoglycemic agents, some patients do not receive the full advantages of current methods due to several restrictions, such as medication costs, accessibility, and concern about the adverse effects of drugs (Sasani et al., 2021). Due to the potentially severe complications of DM, recognizing new applicable approaches for prevention and controlling DM is critical. Identifying and utilizing functional foods (FFs) is one of these new strategies (Mirmiran et al., 2014), where FFs are products in the form of food, not drugs, which provide positive health effects when they are consumed in a normal amount in a usual diet (Amiri Ardekani et al., 2020).Throughout history, acorn, the oak fruit, has been considered as a food and is a part of the usual daily diet in various regions, globally (Burlacu et al., 2020). Acorn contains notable amounts of carbohydrates, protein, and unsaturated fatty acids, such as oleic acid (Taib & Bouyazza, 2021). Moreover, it contains a high amount of phenolic compounds, saponins, and tannins (Şöhretoğlu & Sakar, 2004), which confers antidiabetic effects by enhancing