Insulin resistance syndrome and type 2 diabetes mellitus

Abstract

Patients with type 2 diabetes mellitus have an elevated risk of morbidity and mortality from cardiovascular disease. This risk is partly attributable to an increased prevalence of classic coronary artery disease risk factors and partly because of hyperglycemia itself and a highly atherogenic lipid profile. The altered composition of lipoproteins and lipids in type 2 diabetic patients, termed diabetic dyslipidemia, is characterized by: (1) elevated levels of triglyceride; (2) normal levels of total and low-density lipoprotein cholesterol (LDL-C); (3) reduced levels of high-density lipoprotein cholesterol (HDL-C); (4) elevated levels of apolipoprotein B; (5) a preponderance of small, dense LDL particles; and (6) increased levels of cholesterol-rich very-low-density lipoprotein. In most cases, diabetic dyslipidemia is preceded by hyperinsulinemia resulting from insulin resistance. Because patients with type 2 diabetes and insulin resistance are at a markedly increased risk of atherosclerosis, and because strict control of glycemia has proved beneficial in reducing microangiopathy but not macroangiopathy, treatment of diabetic dyslipidemia should be aggressive. Target levels have, therefore, been set at <2.6 mmol/L (100 mg/dL) for LDL-C, <2.3 mmol/L [200 mg/dL] for triglycerides, and >1.15 mmol/L (45 mg/dL) for HDL-C. Trial data suggest that these target levels are likely to be achieved with statins, if necessary, in combination with fibrates or nicotinic acid derivatives. Furthermore, in large-scale clinical trials (eg, Scandinavian Simvastatin Survival Study [4S] and the Cholesterol and Recurrent Events [CARE] study), it has been demonstrated that lipid lowering can appreciably reduce cardiovascular events in diabetic patients.