Considering the effects of oat (Avena sativa L.) and barley (Hordeum vulgare L.), and their importance in the prevention and control of diabetes mellitus (DM) and cardiovascular diseases, hence the study aims to investigate the effect of adding oat and barley to the diet of hyperglycemic rats and their effects on blood glucose, total cholesterol (TC), High Density Lipoprotein (HDL) and low Density Lipoprotein (LDL) levels, and to examine the effect of mixing flour of wheat with oat and barley on rheological properties of the bread dough, and to evaluate the sensory attributes of baked breads prepared from these mixtures. Thirty male Sprague Dawley rats were divided into five groups (six rats each): Body weight gain and food intake were measured and the Feed Efficiency Ratio (FER) was calculated. Animals were lightly anesthetized at the end of the experimental period and blood was collected. Blood glucose, total cholesterol (TC), HDL and LDL were estimated. For measurement of dough's rheological properties, dough prepared from various mixtures of wheat, oat and barley flour were subjected to Farinograph and Extensograph tests, and the baked bread was subjected to orgranoleptic evaluation. The results showed that body weight gain for groups of rats fed on 40% oat, barley or their mixture were lower than that of positive control group. Rats groups fed on oat, barley and their mixture showed significant (P <0.01) decrease in blood glucose level when compared with the positive control group. Serum cholesterol and LDL levels were significantly (P<0.01) decreased in groups fed on oat, barley and their mixture in comparison with positive control value, on the other hand serum HDL level increased significantly in experimental groups when compared to the value of positive control. Replacement of wheat flour with 40% of oat or barley increase the water absorption and the dough resistance and extensibility decreased as a consequence of adding either oat or barley flour, wheat  flour bread  has higher acceptance score, followed by mixture of (wheat 60% + oat 20% +barley 20%).