Corni Fructus, also known as the fruit of Cornus officinalis Sieb. et Zucc., has long been used as a traditional Chinese medicine and is widely consumed as a nutritional food in the form of function drink and wine. Recently, Corni Fructus has attracted considerable interest because of its anti-diabetic effects. A systematic phytochemical investigation of Corni Fructus was performed to find anti-diabetic components, which led to the isolation of 10 unreported iridoid glycosides, cornusdiglycosides A - J (1-8, 9a/9b and 10a/10b). Their chemical structures were determined through spectroscopic analysis (ultraviolet [UV], infrared [IR], high-resolution electrospray ionisation mass spectroscopy [HRESIMS], one-dimensional [1D] and two-dimensional [2D] nuclear magnetic resonance [NMR]). Such morroniside-type diglycosides were first reported from natural sources, and all isolates were evaluated for alpha-glucosidase inhibitory activity. The results showed that all compounds (1-10) exhibited alpha-glucosidase (from Saccharomyces cerevisiae) inhibitory activities with IC50 values ranging from 78.9 +/- 4.09 to 162.2 +/- 9.17 mu M, whereas acarbose, the positive control, displayed alpha-glucosidase inhibitory activity with IC50 value of 118.9 +/- 7.89 mu M.