Pharmacological Regulation of Dyslipoproteinaemia in Insulin Resistant States

Dyslipidaemia is a common and consistent abnormality in insulin resistant subjects with obesity and type 2 diabetes mellitus associated with increased risk of cardiovascular disease. Lipoprotein metabolism is complex and abnormal plasma concentrations can result from alterations in the rates of production and/or catabolism of diverse lipoprotein particles. Our understandings of the dysregulation and therapeutic regulation of lipoprotein transport in insulin resistant states has relied on the application of advances in stable isotope and modelling methods. Dysregulation of lipoprotein metabolism in these circumstances may be caused by a combination of overproduction of VLDL apolipoprotein (apoB) B- 100 and VLDL-apoC-III, decreased catabolism of apoB-containing particles, and increased catabolism of HDL apoA-I particles. These abnormalities may be consequent on a global metabolic effect of insulin resistance and accumulation of visceral fat. Several pharmacological treatments, such as statins, fibrates or fish oil can correct the dyslipidaemia by diverse kinetic mechanisms of action, including decreased secretion of apoB and apoC-III, and increased catabolism of apoB, as well as increased secretion and decreased catabolism of apoA-I. Newer agents, including insulin sensitizers, cholesterol absorption inhibitors, CETP inhibitors, peroxisome proliferator-activated receptor-delta agonists and endocannabinoid- 1 receptor blockers, have also been shown to improve plasma lipid and lipoprotein abnormalities in insulin resistant states; their mechanisms of action are at present being investigated. Rimonabant is the endocannabinoid receptor blocker shown to decrease cardiometabolic risk in insulin resistant subjects. The complementary mechanisms of action of different agents support the use of combination regimens in treating dyslipoproteinaemia in subjects with central obesity and type 2 diabetes.