Statins and diabetes

Abstract

Lipid abnormalities play an important part in raising the cardiovascular risk in diabetic subjects. The main components of diabetic dyslipidemia are increased plasma triglycerides, low concentration of high-density lipoprotein cholesterol, preponderance of small, dense low-density lipoprotein, and excessive postprandial lipemia. Small, dense low-density lipoprotein, the elevation in remnant triglyceride-rich lipoprotein particles, and the low high-density lipoprotein are the most powerful atherogenic components. The coexistence of these three factors strongly aggravates the lipid accumulation in the arterial wall and the formation of atherosclerotic plaques. The position of diabetes in cardiovascular risk assessment has been recently reviewed in the Harmonized Clinical Guidelines on Prevention of Atherosclerotic Vascular Disease. In general, patients with diabetes carry a high risk for cardiovascular disease, but the absolute risk varies depending on the type of diabetes, age, and population baseline risk. The Adult Treatment Program III (ATP III) and the American Heart Association have designated diabetes as a high-risk condition and recommended intensive risk-factor management. Concerning therapeutic targets, both ATP III and the American Diabetes Association (ADA) guidelines have identified low-density lipoprotein cholesterol as the first priority of lipid lowering, and the optimal level was set at less than 2.6 mmol/L (100 mg/dL). There is strong evidence, coming from landmark secondary prevention studies, that LDL lowering in people with diabetes is associated with significant clinical benefits. The benefits of statin therapy in type 2 diabetics can no longer be questioned. Ongoing clinical trials will help clarify the question of whether increasing high-density lipoprotein cholesterol with fibrates in the presence of low low-density lipoprotein levels (lower than 3.4 mmol/L, or 130 mg/dL) will be more beneficial than statin therapy alone. The new paradigms in risk-reduction therapies for type 2 diabetic subjects are focused on cardiovascular disease prevention, rather than only on glucose or lipid control. Therapeutic lifestyle changes are considered primary therapies for hyperglycemia and coexisting metabolic syndrome, which can be diagnosed in more than half of type 2 diabetes subjects. New perspectives of lipid management in type 2 diabetes should take into account that insulin resistance, increased lipolysis, and overproduction of large, buoyant, very low density lipoprotein particles are at the base of diabetic dyslipidemia. Accordingly, drugs acting in the regulatory steps of very low density lipoprotein assembly should be developed. Activation of peroxisome proliferator activated receptor alpha (PPARalpha), as occurs with fibrates, lowers free fatty acids (FFAs) and triglyceride levels. PPARgamma agonism, as demonstrated by the thiazolidinediones, increases triglyceride lipolysis, FFA transport, and conversion of FFAs to triglycerides. As separate activation of PPARalpha and PPARgamma improves lipid metabolism, the development of new drugs integrating PPARalpha and PPARgamma activity (PPAR-alpha/gamma agonists) is a promising line that may further improve insulin resistance, FFA metabolism, and consequently, atherogenic diabetic dyslipidemia.