In 2021, there are approximately 537 million adults ageing 20?79 years affected by diabetes worldwide and the number is rising rapidly, hence it is important to manage and control diabetes mellitus and its associated complications. Food is one of the key factors in preventing and combating diseases such as diabetes. Both as a food and an herbal medicine, Polygonum multiflorum (PM) has been used as an anti-aging tonic, for hair darkening in traditional Chinese medicine for several centuries. The recent research effort of PM has been focused on antioxidant, anti-ageing and anti-tumor properties. In the present study, we utilized the traditional processing of harvested raw PM, and identifi ed several stilbene components and then evaluated the potential anti-diabetic effects of the processed PM extract (PME). PME (0.075%) was given to diabetic mice (KK CgAy/J) in drinking water and after 7 weeks, PME-treated mice had signifi cantly lower glucose levels than mice in the diabetic control group (P < 0.01). The mechanism was explored with ELISA and Western blotting and results suggested that the effect was through maintaining β-cell function.