Diabetologists in Sahakara Nagar, Bangalore • Low-density lipoproteins Sixty to seventy per cent of total cholesterol is transported as LDL, and total cholesterol measurements usually reflect LDL levels. In both males and females, coronary heart disease risk is proportional to LDL and total cholesterol. As seen above, LDL supplies cholesterol to peripheral tissues. High concentrations of LDL in the serum accelerate atheroma by interacting with damaged endothelium. Oxidation of LDL accelerates this process. A total cholesterol of 5.5 mmol/L, or LDL of 3.5 mmol/L, is usually considered the upper limit of normal but even these levels seem to be responsible for an increased population risk of atheroma. Populations with lower average levels than these have less coronary disease. Lower levels are beneficial for patients with established coronary disease or multiple risk factors. It is not yet clear whether the lowering of total cholesterol to less than 4.0 (LDL 2.0) provides further benefit or whether a target level is indeed the correct approach. Trials of more aggressive cholesterol lowering are underway.14 Although a reduced HDL level (< 1) is associated with increased risk, there is no evidence as yet that raising HDL has beneficial effects. An elevation of triglyceride levels (> 1.7) is also considered a marker of increased risk, but there is no evidence to what level they should be reduced. Exogenous Endogenous Chylom. (TG & Chol.) LDL receptor tissues HDL and FFA Endogenous chol. Endothelium (Lipoprotein lipase) Endothelium (Lipoprotein lipase) FFA FFA LDL IDL LIVER Plasma LCAT VLDL Monog. Chylomic. remnant (Chol.) Intestinal cell Carries 3/4 of total chol. Dietary TG