Almost all of the risk factors for arteriosclerosis and coronary heart disease identified in population studies are overrepresented in diabetes. Of these risk factors, plasma lipids and lipoproteins are the target for altered dietary habits, particularly regarding fat. Such an alteration must be qualified with an understanding of the relationship between diabetes mellitus and lipoprotein metabolism and evidence of a favorable outcome of a fat-modified diet on this relationship. In seeking a revision of the current dietary fat recommendations of the American Diabetes Association, we have addressed five major questions. Is the serum lipid or lipoprotein concentration in diabetes different from that of the nondiabetic population? Are the familial or genetic forms of hyperlipidemia coinherited and/or overrepresented in diabetic subjects? What is the mechanism of the lipid/lipoprotein disorder in diabetes, and to what extent could it be related to the diabetic metabolic milieu? What is the effect of antidiabetic treatment on plasma lipids and lipoprotein metabolism? What evidence is there that a modified-fat diet could exert favorable benefits over and above what could be achieved by optimal antidiabetic therapy? This article outlines the revised dietary fat recommendations of the American Diabetes Association Nutrition Task Force and their rationale.