The protective effects of freeze-dried privet (Ligustrum obtusifolium) fruits (PFs) were observed in streptozotocin (STZ)-induced diabetic rats on a high fat diet by measuring levels of blood glucose, serum insulin, fructosamine, and hepatic reactive oxygen species generating and scavenging enzyme activities. A PF-supplemented diet was prepared by mixing an AIN-76 diet with powdered PF (final concentration, 1% or 2%). It was fed to STZ-induced diabetic rats on a high fat diet for 6 weeks. Diabetic animals receiving the PF-supplemented diet showed a significant increase in body weight, feed efficiency ratio, liver, kidney, and heart weight, and serum glucose, insulin, and fructosamine levels compared with high fat diet-fed diabetic animals. The treatment with PF showed improved hepatic glutathione S-transferase, superoxide dismutase, and xanthine oxidase activities as well as glutathione and lipid peroxide levels in the diabetic animals. Intracellular swelling and vacuole formation in diabetic pancreatic $eta$- and $delta$-cells were ameliorated by the PF-supplemented diet. Furthermore, necrosis of tubular epithelial cells and dilatation of luminal space in diabetic kidneys exhibited near-noninjured condition. This is the first time an antihyperglycemic effect of L. obtusifolium fruit in STZ-induced diabetic rats has been identified.