Dyslipidaemias, insulin resistance and atherosclerosis

Recent studies have demonstrated that insulin resistance, a proportionate decrease in insulin action at all insulin concentrations, is associated with clustering of many cardiovascular risk factors, particularly hyperlipidaemias. Already epidemiological studies have indicated that high insulin levels are related to low high-density lipoprotein (HDL) cholesterol and high total and very-low-density lipoprotein (VLDL) triglyceride levels. Recent studies based on the direct quantification of insulin resistance by the euglycaemic clamp method have verified these findings. In contrast, insulin resistance seems not to be associated with high low-density lipoprotein (LDL) cholesterol. Abnormalities in HDL and VLDL levels may contribute to accelerated atherosclerosis, but there is evidence that insulin resistance is also directly associated with asymptomatic atherosclerosis. Thus, prevention of atherosclerosis should not be targeted only to the lowering of LDL cholesterol, but also to the reduction of the degree of insulin resistance either with diet, weight reduction, regular exercise or drug therapy.