Lipoprotein metabolism in non-insulin-dependent diabetes mellitus

The risk and incidence of vascular disease in patients with non-insulin-dependent diabetes mellitus (NIDDM) are higher than those of the nondiabetic population. The modest changes in the concentration of plasma lipids that have been reported do not fully explain this increased risk of vascular disease in diabetics. However, there have been numerous reports of changes in the composition and structure of plasma lipoproteins in patients with NIDDM that render these lipoproteins more atherogenic. Changes in the subpopulation distribution of plasma low-density lipoprotein and high-density lipoprotein, which have been shown to be associated with vascular disease, have been also observed in patients with NIDDM. Although the precise mechanisms that underlie the origination of alterations in the subpopulation distribution of plasma lipoproteins have not been fully elucidated, evidence strongly suggests that changes in the activities of key enzymes in lipoprotein metabolism may contribute to the altered lipoproteins. This review describes the effects of diabetes, along with the confounding effects of obesity and insulin resistance, on the metabolism of plasma lipoproteins. in addition, the changes in the function of enzymes that are involved in the metabolism of cholesterol and triglycerides of circulating lipoproteins that occur in NIDDM are presented. Although new insight on the effects of diabetes and its complications on the metabolism of lipoproteins has been gained, there are still gaps that need to be filled to complete our understanding of the strong relationship between diabetes and vascular disease. (C) Elsevier Science Inc.