Non-HDL as a Valid Surrogate Marker of Small Dense LDL in a Young Indian Population

Management of triglycerides, non-high density lipoprotein cholesterol and high density lipoprotein cholesterol

Dyslipidaemia characterised by elevated total cholesterol/LDL-C, triglyceride or both or decreased HDL-C is an important risk factor for the development of ASCVD. Atherogenic dyslipidaemia characterised by high TG, low HDL-C and elevated small dense LDL (sdLDL) is more prevalent in Asian Indians. Normal level of TG is generally considered as <150 mg/dl. Hypertriglyceridemia is closely associated with obesity, metabolic syndrome and diabetes mellitus. Goals of management of hypertriglyceridemia are to lower the risk of atherosclerotic cardiovascular events and reduce the risk of pancreatitis. Lifestyle modification is important. In severe hypertriglyceridemia, TG lowering pharmacotherapy is important to prevent pancreatitis. In mild to moderate hypertriglyceridemia, pharmacotherapy is employed only if associated with ASCVD or high risk factors and not controlled with lifestyle modifications and statins. Non-High Density Lipoprotein Cholesterol which estimates the cholesterol content of the atherogenic apoB containing lipoproteins, measured as total cholesterol minus HDL-C is equivalent to LDL-C in ASCVD risk assessment and superior to it in those with mild to moderate hypertriglyceridemia. Some international guidelines, have included measurement of non-HDL-C as primary therapeutic target for patients with ASCVD. Low HDL cholesterol is common in Indians. Despite evidence of inverse relationship between HDL-C and cardiovascular events, HDL-C as a causative factor for development of atherosclerosis is unproven. Therapeutic strategies directed at increasing HDL-C levels have not been shown to have cardiovascular benefits and hence HDL-C is currently not a target for drug-based treatment.

Triglyceride/low-density-lipoprotein cholesterol ratio is the most valuable predictor for increased small, dense LDL in type 2 diabetes patients

Background

Small, dense low-density lipoprotein (sd-LDL) increases in type 2 diabetes patients and causes arteriosclerosis. Non–high-density-lipoprotein cholesterol (non–HDL-C) is thought to be useful for predicting arteriosclerosis and sd-LDL elevation; however, there are no data about whether the triglyceride /low-density-lipoprotein cholesterol (TG/LDL-C) ratio is a valuable predictor for sd-LDL.

Methods

A total of 110 type 2 diabetes patients with hypertriglyceridemia were analyzed. No patients were treated with fibrates, but 47 patients were treated with statins. LDL-C was measured by the direct method. LDL-migration index (LDL-MI) using electrophoresis (polyacrylamide gel, PAG) was calculated, and a value ≥0.400 was determined to indicate an increase in sd-LDL. Simple regression analyses were carried out between LDL-MI and lipid markers. Receiver operating characteristic curves of lipid markers for predicting high LDL-MI were applied to determine the area under the curve (AUC), sensitivity, specificity, and cut-off point.

Results

LDL-MI correlated negatively with LDL-C (P = 0.0027) and PAG LDL fraction (P < 0.0001) and correlated positively with TGs, non–HDL-C, TG/LDL-C ratio, TG/HDL-C ratio, and non–HDL-C/HDL-C ratio among all study patients. Similar results were obtained for patients analyzed according to statin treatment. The AUCs (95% confidence interval) were 0.945 (0.884-1.000) for TG/LDL-C ratio and 0.614 (0.463-0.765) for non–HDL-C in patients without statins (P = 0.0002). The AUCs were 0.697 (0.507-0.887) for TG/LDL-C and 0.682 (0.500-0.863) for non–HDL-C in patients treated with statins. The optimal cut-off point for TG/LDL-C ratio for increased LDL-MI was 1.1 (molar ratio) regardless of statin treatment. The sensitivity and specificity of the TG/LDL-C ratio (90.0 and 93.9%, respectively) were higher than those of non–HDL-C (56.7 and 78.8%, respectively) in patients without statins.

Conclusions

The TG/LDL-C ratio is a reliable surrogate lipid marker of sd-LDL and superior to non–HDL-C in type 2 diabetes patients not treated with statins.