Fasting Ramadhan is one of religious obligation for every adult Moslems in the world. The changes of dietary pattern, sleep, rest, and physical activity during Ramadhan influence the diabetic’s blood glucose level. Education program to enhance the ability of the patients to manage their dietary behavior during Ramadhan is critical. This was quasy experimental study with one group using pre-and post test to examine the effect of fasting Ramadhan dietary management program on dietary behavior among diabetic patients in outpatient department of PKU Muhammadiyah Yogyakarta. Twenty three type 2 DM patients received educational program and educational booklet participated in this study through accidental sampling. The data were collected by using questionnaires that were developed by the researcher. Wilcoxon Signed Rank Test was used to analyze the data. The result of the study showed that most of the respondents were female with average age 65,5 years old and duration of DM 5,4 years. There was a significant dietary behaviors before and after the intervention (M = 24,5, SD = 1,5, p < 0.05). In conclusion, fasting Ramadhan dietary management program was effective to improve the dietary behaviors during Ramadhan. Diabetic patients have to check their blood glucose, learn about complication and its management during fasting Ramadhan. Further research encompassing more respondents is needed.