Aldose reductase (AR) is an NADPH dependent enzyme that catalyses the reduction of the aldehyde to the corresponding alcohols. Diabetic complications including neuropathy, nephropathy, cataracts and retinopathy are considerately caused by accumulation of sorbitol, which is produced from glucose by AR in polyol pathway. The aim of AR inhibitor therapy is to normalize the elevated flux of blood and sorbitol through the polyol pathway in the target tissue. A large number of inhibitors have been prepared synthetically, and some of them are used therapeutically. However, none of them is satisfactory. From the plants, many AR inhibitors have been found, which are discussed in this review. By the structure based functioning of AR and its inhibitors, some will be developed promising in the treatment of diabetic complications. The main structural features of the inhibitors will be a polar head group and a hydrophobic ring system. The plants that contain the AR inhibitors may prevent from diabetic complications.