Lipid and lipoprotein abnormalities in non-insulin-dependent diabetes mellitus (NIDDM) include particularly elevated levels of total and very-low-density lipoprotein (VLDL) triglycerides and reduced levels of high-density lipoprotein (HDL) cholesterol. Total and low-density lipoprotein (LDL) cholesterol levels are usually normal if glycemic control is adequate. The worsening of glycemic control deteriorates lipid and lipoprotein abnormalities and particularly total and LDL cholesterol levels are often elevated in patients with poor glycemic control. According to prospective population-based studies total cholesterol is a powerful risk factor for coronary heart disease (CHD) in NIDDM patients as in nondiabetic subjects. In contrast, high total triglycerides and low HDL cholesterol may be even stronger risk factors for CHD in NIDDM patients than in nondiabetic individuals, but more prospective studies are needed to substantiate this view. Compositional changes in LDL and VLDL particles may further increase the risk for CHD but epidemiologic data are missing to support this notion. Preliminary data from the Scandinavian Simvastatin Survival Study including 202 diabetic patients seem to indicate that diabetic patients benefit from simvastatin treatment equally to nondiabetic subjects.