Omentin is a novel adipokine produced preferentially by visceral adipose tissue. Omentin was recently shown to be involved in the development of obesity-associated insulin resistance and type 2 diabetes mellitus in human and animal models. The aim of this research is to identify the effect of omentin administration on glucose and lipid metabolism in experimental animals both in normal conditions and in experimentally induced diabetes mellitus type 1 and type 2. Design: A total number of 48 healthy adult male albino rats were used to study the effect of daily intraperitoneal (i.p) injection of omentin in a dose of 8 μg/Kg for 7 days on some metabolic parameters including glucose and lipid metabolism in experimental animals. Results: The results of this study showed that the mean values were found to be non-significant (P > 0.05) for all parameters on treatment with Omentin in both normal conditions when compared with control group and in Streptozotocin (STZ) induced Diabetic group when compared with that of STZ Induced Diabetic group. In STZ Induced Diabetic Insulin&Omentin Treated group, it was found that there were significant decrease in levels of Serum glucose, HOMA-IR, cholesterol, LDL cholesterol and Serum Triglycerides and significant increase in HOMA β and HDL cholesterol when compared with that of STZ Induced Diabetic group treated with Omentin only and of STZ Induced Diabetic group treated with insulin only. In addition, in High Fat Diet (HFD)-fed diabetic group – Omentin Treated), the mean values were found to be significantly lower for Serum glucose level, HOMA-IR, cholesterol level, LDL cholesterol level and Serum Triglycerides level and significantly higher for HOMA β and HDL cholesterol level with no significant change in Serum insulin when compared with that of HFD-fed diabetic group - control group). No significant change in BMI in all studied groups. Conclusion: The results of this study suggest that omentin improves glucose and lipid metabolism in the pathological diabetic conditions (type 1 DM and type 2 DM) with no significant effect on anthropometric measures in both types. Accordingly, insulin-mimetic, insulin-like, or insulin sensitizer effect of omentin might be assumed.