Introduction: Diabetes mellitus is a metabolic disorder of multiple etiologies characterized by chronic hyperglycemia with disturbances of carbohydrate, fat and protein metabolism resulting from deficits in insulin secretion, insulin action or both. During the past decade and the present time, diabetes mellitus has emerged as an important clinical and public health problem throughout the world Objective: To assess the dietary habit and knowledge of type 2 diabetic patients on healthy diets/life style modification among diabetic clients attending diabetic follow up clinic in selected public health in Addis Ababa, Ethiopia. Methodology: In this study a cross sectional descriptive study design was employed and data were collected from January 2017 to March 2017 using interview method. A total of 422-sample size were selected, Pre-tested and structured. Questionnaires were used to collect data. Collected data were analyzed using SPSS version 20. Appropriate statistical methods were used to test for any associations. Results: Among 422 patients, 377 respondents responded and making a response rate 89%. We have found 181(48%) of them were Males and the remaining 196 (52%) respondents were Females. Conclusion: In this study, knowledge on the cause of diabetics is high and a higher level on the prevention mechanism but a significant number of participants did not do physical exercise on a weekly base due to different reasons. Recommendation: Awareness should be carried out to patients on regular physical activity in order to maintain ideal physical weight by health professions. Health professions on healthy diet and life style modification should give health education