Fat has traditionally been attributed to causing weight gain and increasing insulin resistance, which has led people to think that it has a direct relationship with diabetes. However, according to recent studies it was found that fat does not have a connection with insulin sensitivity, and in several observational studies, total fat intake is not associated with diabetes risk. Many academic societies, based on established research, have reported that the quality of fat is more important than total fat intake. Although the suggested daily intake varies, most say to reduce the intake of saturated fat and trans fat in order to prevent coronary heart diseases. According to the 2013 National Health and Nutrition Examination Survey, Koreans' fat intake made up 21.2% of their daily calorie intake. Although not as high as those in western countries, the intake of fat especially that coming from animals has been quite high among young people. According to the Korean Society for the Study of Obesity and the Korean Society of Lipidology and Atherosclerosis, it is best to keep daily fat calorie intake under 30% of the total daily calorie intake, and to avoid low quality fats, as the quality is thought to have a more direct impact than the quantity of fat. In order to prevent cardio vascular diseases, balanced intake of healthy fatty acids is needed. In this paper we will review the influence of fat, both in quality and quantity, on coronary heart diseases of diabetes patients.