We support the general understanding that deleterious effects induced by hyperglycemia in rats would be alleviated by means of antioxidant treatment. Also, we have been supported and encouraged by many explorations on the usage of fullerenols for treating diabetic complications. Our present study aims to examine the potentials of fullerenols against diabetes in streptozotocin-induced diabetic rats. Animals were intraperitoneally administered with fullerenols for 15 days and then sacrificed. Following parameters were assessed: blood glucose, insulin concentration, levels of redox-related parameters, liver and kidney function biomarkers, glycogen contents, carbohydrate metabolic enzyme activities and histopathological analysis. As expected, fullerenols exhibited the well-known anti-oxidative property via decreasing MDA, increasing SOD, GSH-Px and CAT levels. Fullerenol treatment also showed a slight improvement in liver and kidney functional biomarkers, inferring a marginal hepatorenal protection. However, there were insignificant changes in levels of blood glucose, insulin, the pathological state of the necrotic islets. Herein, our results revealed that fullerenols failed to improve the function of pancreas and reverse the hyperglycemia in streptozotocin-induced diabetic rats in spite of a potent antioxidant role. Our study suggested that neither diabetes nor its complications could benefit from fullerenol administration.