Dietary therapy is a basic and emphasized treatment for diabetes. Several clinical studies have shown that diet can play a major role in preventing and managing diabetes. The purposes of this study were to evaluate the dietary behavior and to find solutions to barriers of diabetes mellitus patients. From February to July in 2007, questionnaires were distributed to one hundred and ten patients who were diagnosed DM by physicians and excluded first coming out-patients. One hundred and three data were used for statistical analysis using SPSS/Win 12.0. The main results of this study included the following: To measure dietary behaviors and barriers, a five point scale was used with the following labels: 'strongly yes', 'yes', 'fair', 'no', 'strongly no'. Thirteen dietary behaviors related to diabetes were grouped into the following 4 factors using factor analysis; 'taste control factor', 'blood glucose influence factor', 'practice volition factor', and 'exercise factor'. The mean scores of 4 factors were 3.88, 3.48, 3.55, 3.21, respectively. The 'taste control behaviors' score of subjects who had practiced diet therapy (4.00) was higher than those who had not practiced diet therapy (P < 0.05). The 'blood glucose influence behaviors' score of subjects who had nutrition education (3.59) was higher than those who had no nutrition education (P < 0.05) and subjects who had practiced diet therapy showed higher score (3.59) than those who had not practiced diet therapy (P < 0.05). 'Exercise behaviors score' of subjects who were over 60 (3.59) was the lowest (P < 0.05). Subjects who had nutrition education showed higher 'exercise behaviors' scores (3.38) than those who had no nutrition education (P < 0.05). Subjects who had practiced diet therapy showed higher 'practice volition behaviors' scores (3.72) than those who had not practiced diet therapy (P < 0.001). Subjects who were over weight showed the highest 'practice volition behaviors' scores (3.78) concerning BMI (P < 0.05). In conclusion, this study expected that Nutrition educators (Dietitian) applied to patient effective nutrition education and counseling through evaluation of Dietary behaviors and barriers considered management types and ecological factors of diabetes patients. Also diabetic patients were easy to change dietary habits because they formed behaviors through education and counsel and there were positive effects in their blood glucose control through removing barriers related to dietary therapy.