Effects of simvastatin on fasting and postprandial triglyceride-rich lipoproteins in patients with type I diabetes mellitus

Postprandial triglyceride metabolism in diabetes mellitus

Individuals with diabetes have a two to four times higher risk of cardiovascular morbidity and mortality than nondiabetics. Patients with both type 1 and type 2 diabetes share a similar risk. Studies in individuals with type 1 diabetes have shown a decreased clearance of postprandial triglyceride-rich lipoprotein particles of abnormal composition. Particles isolated from diabetic individuals show abnormal composition and an increased tendency to cause cholesteryl ester accumulation in macrophages and are therefore potentially atherogenic. Various interventions may alter these abnormalities and improve the atherosclerotic risk. These include adopting a high-carbohydrate diet over a high monounsaturated diet, improving glycemic control, infusing insulin intraperitoneally, and using pharmacologic therapies such as the statins.

Increased atherosclerosis in diabetic dyslipidemic swine: protection by atorvastatin involves decreased VLDL triglycerides but minimal effects on the lipoprotein profile

Male Yucatan swine were allocated to four groups (n = 5-6 pigs per group): low fat (3%) fed control, high fat/2% cholesterol (CH) fed (HF), high fat/CH fed with alloxan-induced diabetes (DF) and DF pigs that were treated with atorvastatin (80 mg/day; DF+A). Pigs were fed two meals per day and daily insulin injections were used in diabetic pigs to maintain plasma glucose between 250 and 350 mg/dl. Diabetic dyslipidemic (DF) pigs exhibited greater coronary atherosclerosis and increased collagen deposition in internal mammary artery compared with normoglycemic hyperlipidemic pigs. Although total and LDL CH concentrations did not differ, triglyceride (TG) were increased in DF pigs and FPLC analysis indicated that the LDL/HDL CH ratio was significantly increased in DF compared with HF pigs. The LDL fraction of DF pigs contained larger, lipid enriched particles resembling IDL. Consumption of the high fat/CH diet caused a moderate increase in the percentage of 14:0 fatty acids in plasma lipids and this was compensated by small-moderate declines in several unsaturated fatty acids. There was a significant increase in phospholipid arachidonic acid in DF compared with HF pigs. Atorvastatin protected diabetic pigs from atherosclerosis and decreased total and VLDL TG, but exerted minimal effects on the FPLC lipoprotein and plasma fatty acid profiles and plasma concentrations of total and LDL CH, vitamin A, vitamin E, and lysophosphatidylcholine. Across all groups the plasma CH concentration was positively correlated with hepatic CH concentration. These findings suggest that atorvastatin's protection against coronary artery atherosclerosis in diabetes may involve effects on plasma VLDL TG concentration. Lack of major effects on other lipid parameters, including the LDL/HDL ratio, suggests that atorvastatin may have yet other anti-atherogenic effects, possibly directly in the vessel wall.

Diabetes: statins, fibrates, or both?

Cardiovascular disease is the leading cause of mortality in patients with type 2 diabetes. Among the many factors that are involved in the pathogenesis of atherosclerosis in diabetic patients, dyslipidemia plays a major role. It is characterized by an increase in triglycerides, a decrease in high-density lipoprotein cholesterol and normal or mildly elevated low-density lipoprotein cholesterol. The management of patients with diabetic dyslipidemia is difficult because we lack studies specifically designed for diabetic patients. Thus, strategy has to rely on post hoc analyses of landmark intervention trials, which usually include only a small number of diabetic patients, or on rare trials enrolling small cohorts of diabetic patients. When lifestyle changes fail, monotherapy should be tried first with either a statin or a fibrate, depending on triglyceride level. If lipid target values are not reached, a combination therapy can then be initiated, with close follow-up of potential side effects.