Pterocarpus marsupium has been used in the treatment of toothache, diarrhoea, heartburn, urinary tract infections, boils, sores and skin diseases. P. marsupium has been used for many years in the treatment of diabetes mellitus. Pterostilbene was found to be one of the active constituents in the extracts of the heartwood of Pterocarpus marsupium. Pterostilbene, a phenolic compound derived from resveratrol, possesses greater bioavailability than its parent compound due to the presence of two methoxyl groups. In this study, the beneficial effects of pterostilbene on diabetes, liver steatosis and dyslipidemia are summarized. Pterostilbene is a useful bioactive compound in preventing type 1 diabetes, insulin resistance and type 2 diabetes in animal models. Plants have received much attention as sources of biologically active substances. Tetrahydrocurcumin (THC) is a hydrogenation product of curcumin produced by reducing curcumin in an organic solvent using a metal catalyst. Erythrocytes have specific surface receptors, which have binding characteristics similar to those of the insulin receptor found in classical target tissues for insulin action. Streptozotocin (STZ) causes significant reduction in the number of receptors in erythrocytes and insulin target tissues. Erythrocytes from diabetic control rats show decreased ability to bind to insulin when compared with THC and pterostilbene-treated diabetic rats. High affinity (Kd1), low affinity (Kd2) and kinetic analyses revealed an increase in the average receptor affinity of erythrocytes from pterostilbene and THC-treated diabetic rats compared with diabetic control rats. These results suggest that acute alteration of the insulin receptor on the membranes of erythrocytes occurred in STZ diabetic rats. The effect of THC was more prominent than pterostilbene.