Both risk factors and the incidence of cardiovascular disease are higher in diabetic patients. Total serum cholesterol has the same impact on coronary heart disease (CHD) incidence in diabetic patients as in nondiabetic individuals. Abnormal blood lipids in diabetic patients include elevated very low-density lipoproteins (VLDL) and triglyceride and reduced levels of high-density lipoproteins (HDL). These are associated with obesity and precede the onset of diabetes. Diabetes increases the risk of all clinical manifestations of CHD, has a greater impact in women, and predisposes to cardiac failure and fatal outcome. In men, it predisposes to silent myocardial infarctions. CHD risk reduction in the diabetic patient requires multifactorial control. In evaluating the lipid-induced CHD risk, the level of low-density lipoprotein (LDL) cholesterol is not as valuable as the LDL/HDL cholesterol ratio, which is the most reliable criterion. Triglyceride levels make no independent contribution. Most CHD preventive measures, including weight control, exercise, avoidance of cigarettes, and improvement of glucose tolerance also increase HDL cholesterol, reduced levels of which are chiefly responsible for the poor LDL/HDL ratio in diabetics. Weight control merits a high priority because of its favorable influence on the lipid profile, glucose tolerance, and blood pressure.