Background and Objectives: Diabetes mellitus is among the most common causes of mortality in the world and an important risk factor for chronic kidney disease, foot amputation, ischemic heart disease and blindness among older adults. Diabetic patients mostly develop hyperlipidemia, which can result in cardiovascular diseases. Patient's knowledge, attitude and practices toward diet are the core center for diabetes control and affect their metabolic control and complications. In the present study, we measured nutritional knowledge, attitude and practices and their relations to serum lipids, HbA1C, and fasting blood glucose in diabetic patients of Boirahmad County, southwest of Iran, where many people encounter increasing prevalence of diabetes. Materials and Methods: 198 IDDM patients from the rural and urban areas of Boirahmad County were invited to the health centers to be checked for their fasting blood glucose, serum total cholesterol, serum HDL cholesterol, serum triglyceride and also serum glycosylated hemoglobin. Their knowledge, attitude, and practices toward the diabetic diet were assessed using a validated questionnaire. The obtained scores were classified into three categories (Poor, average, and Good) to show their knowledge, attitude and practice levels, and the serum parameters were compared between the levels to show the relevancies. Results: Our data showed that the patients' knowledge and attitude on diabetic nutrition are mostly at the average level (79.3% and 47.1%, respectively) but their practice scores are mostly at the poor level (43.8%), and just a minor proportion of the patients are at the appropriate levels (15.3, 33, and 23.1% of knowledge, attitude and practices, respectively). In addition, we found a significant reverse relationship between the patients' nutritional knowledge and serum HbA1C (p=0.003), and also between their attitude and serum triglyceride (p<0.05). Conclusions: Our data suggest that the knowledge, attitude and practices of diabetic patients in Boirahmad are not satisfying; also it is necessary to run interventional studies to find the best educational methods to improve, control and manage the diabetics in this area.