What is the consequence of an abnormal lipid profile in patients with type 2 diabetes or the metabolic syndrome?

Patients with type 2 diabetes have an atherogenic lipid profile, which greatly increases their risk of coronary heart disease (CHD) compared with people without diabetes. The largest disparity in lipid levels among people with and without diabetes occurs for high-density lipoprotein cholesterol (HDL-C) and triglycerides: triglycerides tend to be markedly higher and HDL-C moderately lower in patients with diabetes, in contrast to the negligible difference observed in low-density lipoprotein cholesterol (LDL-C) and total cholesterol. However, patients with type 2 diabetes are more likely to have the atherogenic form of LDL-C than people without diabetes, as well as low HDL-C, which restricts reverse cholesterol transport and may also be associated with increased lipid oxidation. Among patients who have suffered a myocardial infarction, increased LDL-C is apparent in early adulthood, whereas a detectable difference in HDL-C levels becomes increasingly apparent with age and most pronounced after age 60 years, compared with healthy controls. Evidence indicates that the increased risk of macrovascular complications of type 2 diabetes begins long before the onset of clinical hyperglycaemia. Despite successful reduction of LDL-C with statin therapy, patients continue to be at increased risk for CHD if their HDL-C levels remain suboptimal, in part due to persistence of enhanced lipid exchange. Observational data suggest that increasing HDL-C should be much more potent therapeutically than a similar proportionate decrease in LDL-C.