Selenium and exendin-4 exhibit antidiabetic effects but with unknown mechanisms. This study investigated the effects of the treatment of diabetic rats with insulin, selenium, their combination, and a combination of exendin-4 and selenium on blood glucose level (BGL) and on the steady-state mRNA levels of IR, GLP-1R and their induced glucose transporters in kidneys of STZ-induced diabetic rats. Diabetes mellitus was induced by the administration of single dose of 65 mg/kg body weight streptozotocin. Diabetic rats were treated with insulin, selenium, insulin and selenium, or exendin-4 and selenium for 6 days. The steady-state mRNA levels of IR, IRS-1, PDK1, PKC, AKT, GLUT2, GLP-1R, GLUT4, and RAF1 were determined by Real-time PCR assay. The results of this study showed significant improvement in the BGL of diabetic rats treated with selenium or insulin with selenium resulted after 5 days of treatment. The treatment of diabetic rats with a combination of exendin-4 and selenium reduced the hyperglycemia in diabetic rats to levels close to the normal BGL after 2, 4, 5, and 6 days of treatment, as compared to that in control rats. Furthermore, the treatment of diabetic rats with selenium resulted in increasing the mRNA steady-state levels of IRS-1, PKC, AKT, and GLUT2 after 6 days of treatment, as compared to diabetic rats received no treatment. The treatment of diabetic rats with the combination of selenium and insulin resulted in increasing the mRNA steady-state levels of PDK1, PKC, and GLUT2 in kidneys after 6 days of treatment, as compared to diabetic rats received no treatment. Also, the treatment of diabetic rats with the combination of selenium and exendin-4 resulted in increasing the mRNA steady-state levels of PKC and GLUT2 after 6 days of treatment, as compared to diabetic rats received no treatment. Therefore, the antidiabetic effects of selenium, insulin with selenium, and exendin-4 with selenium may result from their effects on steady-state mRNA levels of IR, GLP-1R and glucose transporter-2 in kidneys. Keywords: blood glucose levels, diabetes mellitus, exendin-4, glucose transporters, GLP-1R signaling, insulin, IR signaling, rat kidney, selenium, steady-state mRNA levels.