Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. The disease results from the defects of insulin secretion and/or action. Resveratrol is a non-flavonoid polyphenol that naturally occurs as phytoalexin. The shell and stem of Vitis vinifera L. (Vitaceae) are the richest source of this compound. In addition to various in vitro and in vivo studies revealing the effectiveness of resveratrol in DM, there are many clinical trials indicating that resveratrol has the potential to benefit in DM patients. The therapeutic action of this compound in relation to diabetes is complex and involves in several beneficial roles. In view of this, clinical studies are necessary to elucidate these roles. In the near future, the use of resveratrol, alone or in combination with current anti-diabetic therapies, might be a conventional approach to effectively manage DM or its complications. This mini-review provides a critical overview of currently available clinical studies examining the effects of resveratrol in DM last decade.