Background and aim of the study: DM represents an important independent risk factor for the development of and mortality from coronary heart disease (CHD), increasing the risk by    2 to 4 times. According to WHO data, more than 75% of patients with DM die due to vascular accidents. This study investigated the effects of some plants used in Saudi Arabia and some other Arab countries as antidiabetic agents and explores its metabolic effects. Material and Methods: One hundred fifty adult male Albino Rats were divided into six experimental groups each consist of twenty five rats. The first group was considered as a control group. The rest of groups were affected by induction of experimental diabetes by subcutaneous injection of Alloxan. The second group consisted of diabetic rats without any treatment. The third group was treated by the aqueous extract of mixture contains Foenugreek, Nigella sativa and Termis seeds. The fourth group was treated with the aqueous extract of Nigella sativa seeds (100 mg / kg of body weight), while the fifth group was treated with the aqueous extract of Foenugreek seeds (100 mg / kg of body weight). The sixth one was treated with the aqueous extract of Termis seeds (100 mg/kg body weight). After four weeks of treatment, different biochemical parameters were performed including estimation of blood sugar level and serum insulin level. Pancreatic and liver samples were obtained and processed for microscopic and quantitative evaluation after staining the prepared sections with both Heamatoxylin and Eosin as well as special stain for demonstration of the different pancreatic cells in the Islet of the Langerhans. Results: The usage of the mixture or each plant alone corrected the glucose level and insulin level. Microscopically there was definite decrease in the number and diameter of beta pancreatic cells in the diabetic group while the other pancreatic cells were not affected (alpha and delta cells). The use of medicinal plants in the different groups of this study greatly improved such cellular changes and the level of blood sugar level was corrected. Also, improve dyslipidemia present in diabetic rats. The results showed that the activity of the mixture was better when compared with Nigella, Foenugreek or Termis seeds alone. Conclusions: The water extract of the mixture is the most powerful in amelioration hyperglycemia and most of all damage effects of Alloxan on hematological parameters and lipid profile. Also, it can control most of the metabolic risk factors of CAD in diabetic rats. So it is advised to use the plant mixture as an antidiabetic agent rather than the use of each plant separately. Repeating such study with the use of variable doses may be helpful in better evaluation for the required dose.