The growing prevalence of age-related diseases, especially type 2 diabetes mellitus (T2DM) and cancer, has become global health and economic problems. Due to multifactorial nature of both diseases, their pathophysiology is not completely understood so far. Compelling evidence indicates that increased oxidative stress, resulting from an imbalance between production of reactive oxygen species (ROS) and their clearance by antioxidant defense mechanisms, as well as the proinflammatory state contributes to the development and progression of the diseases. Curcumin (CUR; diferuloylmethane), a well-known polyphenol derived from the rhizomes of turmeric Curcuma longa, has attracted a great deal of attention as a natural compound with beneficial antidiabetic and anticancer properties, partly due to its antioxidative and anti-inflammatory actions. Although this polyphenolic compound is increasingly being recognized for its growing number of protective health effects, the precise molecular mechanisms through which it reduces diabetes- and cancer-related pathological events have not been fully unraveled. Hence, CUR is the subject of intensive research in the fields Diabetology and Oncology as a potential candidate in the treatment of both T2DM and cancer, particularly since current therapeutic options for their treatment are not satisfactory in clinics. In this review, we summarize the recent progress made on the molecular targets and pathways involved in antidiabetic and anticancer activities of CUR that are responsible for its beneficial health effects.