Background: Globally, diabetes is a major health problem that can affect people of all ages and all races. However, there is still no cure for diabetes, diet is one of the most important approaches in maintaining controlled glycemic level. Aim: To evaluate the impact of different types of diets on controlling blood glucose level and prevention of complications among patients with type 2 diabetes. Sample:  Purposive sample of 90 patients diagnosed with type 2 diabetes, categorized into 3 groups according to their diet preference as low carbohydrate diet, Ketogenic diet, and vegan diet. Research design: Quasi experimental research design was utilized in this study. Study Setting: This study was conducted in diabetes outpatient's clinic at Kafrelsheikh University Hospital. Tools: one tool was developed to collect data and consisted of three parts as following; Part one to collect patients' sociodemographic data, Part two designed to assess participants` medical data and diabetes related complications, and part three used to assess the effect of diets on certain variables. Results: showed that there was a statistical difference between total HA1C mean scores in relation to time of intervention as mean scores decreased from 6.71 in bassline period to 6.62 and 6.30 in 3- and 6-months post intervention consequently for group following ketogenic diet as (F=8.921&p=<0.05). Conclusion: following healthy nutritional regimen is a significant factor for restoring health for patients with type 2 diabetes. ketogenic diet is the most relevant for patients with type 2 diabetes followed by vegan and low carb diet. Recommendations: nurses emphasize on continuous teaching of patients with type 2 diabetes about different types of diets and its effect on controlling blood glucose level and prevention of complications.