Background:This is an experimental study to evaluate the anti-oxidant, anti-diabetic and anti-inflammatory effectsof thymoquinone in streptozotocin-induced diabetic rat. Material and Methods:A total number of 30 Wistar rats were included in the study. Each group contained n=6 rats. Rats in Group 1 were maintained on normal pellet diet (NPD) and water ad libitum while rats in the remaining groups (2 to 6) were given high-fat diet (HFD). After 4 weeks of high fat diet all rats were fasted from 7 am to 3 pm(118). Rats on normal pellet diet were given citrate buffer and rats on high HFD were given a single intraperitoneal injection of Streptozotocin in the dose of 40 mg/kg BW.11 STZ at a dose of 40 mg/kg was prepared in cold citrate buffer (pH 4.5, 0.1 M) and given intraperitoneally.12 Rats were stabilized after one week of STZ injection. Results:Our analysis for between-group differences in mean weights found statistically significant associationsfor the group A vs. B (p<0.001), A vs. C (p<0.001), B vs. D (p=0.04) and B vs. E (p<0.001). The highest positive mean difference was noted for group B vs. E (68 ± 15.61 g) followed by group B vs. D (48 ± 15.61 g) and group C vs. E (42 ± 15.61 g). Conclusion:Our study involving diabetic rat model to understand the effect of TQ’s anti-diabetic, anti-inflammatory and anti-oxidant properties as compared to metformin showed that the combination of TQ + metformin had superior properties as compared to either of these drugs administered alone. The increasein mean weight was significantly higher in TQ group as compared to the combination group (E) (p<0.001). And among monotherapies, metformin showed a similar effect on weight gain as TQ (p=0.47). Reduction in RBS levels were significantly lower in combination group (E) as compared to TQ alone (p<0.001). And among monotherapies, metformin showed similar effect on lowering of RBS levels as TQ (p=0.48). Reduction in IL-6 levels was significantly lower in combination group (E) as compared to TQ alone (p<0.001). Even among monotherapies, metformin showed a statistically significant lowering of IL-6 levels as compared to TQ (p<0.001). Reduction in MDA levels was significantly lower in the combination group (E) as compared to TQ alone (p=0.03). And among monotherapies, metformin showed similar effect on lowering of MDA levels as TQ (p=0.99).