The plant genus Morus (Mulberry) has been used by humans for many centuries. All parts of the trees are used, but the fruits have the highest nutritional values. Most of the species of this genus were studied for various medicinal and biological activities, as well as many other properties, including chemical composition. Two species, Morus alba and Morus nigra were very extensively investigated, and research reports about them continue to be published very frequently. The chemistry of this plant genus is fascinating. It includes numerous natural products with unique structures and structure-sub-units, making them excellent candidates as organic synthesis starting materials. Many review articles were published about the Morus genus and some of its species, but this article is the most comprehensive regarding antidiabetic activity and insulin regulation. Active natural products are responsible for these activities will be presented, as well as possible and proposed mechanisms of action. Ethnobotanical and ethnomedicinal information related to the antidiabetic activity will be briefly presented. In addition, a thorough discussion section will lead to conclusions, some future directions, and recommendations for research.