Metabolic effects of ten daily doses of standardized extract of Andrographis paniculata leaves (AP) rich in andrographolide were evaluated in a rat model of type-2 diabetes and in diet induced obese rats. AP was administered per-orally as suspension in 0.3% carboxymethylcellulose at doses of 50, 100 and 200 mg/kg/day for 10 consecutive days. Blood glucose, insulin and lipid profile of rats were measured by using enzyme kits. In addition, effects of such treatments on anti-oxidant enzymes activity and histopathological changes in various organs of diabetic rats were assessed. AP treatments reversed body weight losses and increased plasma insulin level in diabetic rats. The anti-oxidant enzymes activity became normal and histopathological changes observed in pancreas, liver, kidney and spleen of diabetic animals were less severe in extract treated groups. On the other hand, hyperinsulinemia and increased body weight gains observed in high fat or fructose fed rats were less severe in the extract treated groups. These observations revealed therapeutic potentials of the extract for treatments of diabesity associated metabolic disorders, and suggest that the effects of the extract on insulin homeostasis depend on the metabolic status of animals. Activation of cytoprotective mechanisms could be involved in its mode of action.