Hyperinsulinemia and insulin resistance: Associations with cardiovascular risk factors and disease

Elevated insulin concentrations is a risk factor for coronary heart disease (CHD), at least among men, and has direct relationships with several CHD risk factors including blood pressure, lipoproteins and body fat distribution. Insulin also stimulates smooth muscle cell proliferation to further enhance its atherosclerotic effects. Hyperinsulinemia and insulin resistance may each mediate different aspects of the insulin CHD link although this remains a controversial issue. Not all studies support an association between hyperinsulinemia/insulin resistance and increased CHD risk factors, particularly those in the elderly and American Indian groups. While some of these 'negative' results are due in part to a reliance on statistical models rather than biologic relationships, insulin/CHD relations may truly differ due to different genetic and environmental determinants of insulin resistance in certain populations. Coronary risk reduction has been disappointing in antihypertensive clinical trials utilizing certain pharmacological agents, which although reducing blood pressure, may act to increase insulin resistance as well as other risk factors. Use of newer classes of drugs as well as the adoption of hygienic means of lowering blood pressure and increasing insulin sensitivity may be required to achieve maximal risk reduction in patients at risk for CHD.