The effects of curcumin and its nano-micelle form on body weight, insulin resistance, adiponectin, and blood biochemical parameters of streptozotocin-induced diabetic rats were studied. Diabetes was induced in fifty male Wistar rats which were divided into five groups treated with 1) no dietary supplements, 2 and 3) 40 and 80 mg curcumin/kg of feed, and 4 and 5) 40 and 80 mg nano-micelle curcumin/kg of feed. A group of ten untreated male Wistar rats was also considered a healthy control group. The serum concentrations of AST, ALT, glucose, insulin, triglycerides, cholesterol, HDL-C, LDL-C, and adiponectin, as well as insulin resistance, were assessed. Body weight and weight of liver, heart, and pancreas were also evaluated. Induction of diabetes increased the serum concentrations of AST, ALT, glucose, triglycerides, cholesterol, LDL-C, and insulin resistance and decreased the serum levels of insulin, adiponectin, and HDL-C, as well as body weight and weight of the heart and pancreas (p < 0.05). Nano-micelle form of curcumin alleviated the negative effects of glucose, lipid profile, and liver enzymes in diabetic rats (p < 0.05). In conclusion, the nano-micelle form of curcumin showed better efficiency compared to curcumin for improving the adverse effects of diabetes. It can be suggested that the nano-micelle form of curcumin at specific doses might be useful for diabetes treatment.