Natural iridoid glycosides, a treasure for drug candidates against type 2 diabetes mellitus pathogenesis

In recent years, type 2 diabetes mellitus (T2DM) has become a global epidemic due to unhealthy lifestyles and genetic heritage. It is widely believed that the pathogenesis of T2DM involves numerous pathological factors including impaired insulin signaling, lipotoxicity, amyloid protein deposition, oxidative stress, and so forth. Although many drugs have been approved, unmet clinical needs should be paid attention to. A variety of iridoid glycosides have been found to possess strong protective effects upon impaired pancreatic function and peripheral insulin resistance. This review summarizes the effects of iridoid glycosides upon T2DM and potential mechanisms, discusses their structure-activity relationship, and analyzes issues hindering further development of iridoid glycosides and their derivatives, thus providing future options for searching and developing drug candidates against diabetes and related diseases.