This study is designed to know the effects of chromium picolinate (CrPic) and melatonin (Mel) each alone and in a combination on high carbohydrate diet‐fed (HCD‐fed) male Wistar rats that exhibit insulin resistance (IR), hyperglycemia, and oxidative stress. Wistar rats have been categorized into five groups. Each group consisted of six male Wistar rats, control rats (group I), HCD (group II), HCD + CrPic (group III), HCD + Mel (group IV), and HCD + CrPic + Mel (group V). Insignificant differences were observed in serum levels of superoxide dismutase, nitric oxide, and zinc in group III, group IV, and group V when each group was compared with group II rats respectively. Significant differences were observed in group III, group IV, and group V when each group was compared with group II in homeostasis model assessment‐estimated IR (P < 0.05, <0.0.05, <0.05), and in the levels of blood glucose (P < 0.05, <0.0.05, <0.05), total cholesterol (P < 0.05, <0.001, <0.001), triacylglycerols (<0.05, <0.001, <0.001), high density lipoprotein cholesterol (P < 0.05, <0.001, <0.001), malondialdehyde (P < 0.05, <0.05, <0.001), catalase (P <0.05, <0.05, <0.05), glutathione (P < 0.05, <0.05, <0.05), Mel (P < 0.05, <0.05, <0.001), and copper (P < 0.05, <0.05, < 0.001). In view of these results, HCD‐fed male Wistar rats that are destined to attain IR and T2DM through diet can be prevented by giving CrPic and Mel administration in alone or in a combination. © 2015 BioFactors, 42(1):106–114, 2016