Apolipoprotein B Is Related to Metabolic Syndrome Independently of Low Density Lipoprotein Cholesterol in Patients with Type 2 Diabetes

Abstract

Background: Increased low density lipoprotein cholesterol (LDL-C) level and the presence of metabolic syndrome (MetS) are important risk factors for cardiovascular disease (CVD) in type 2 diabetes mellitus (T2DM). Recent studies demonstrated apolipoprotein B (apoB), a protein mainly located in LDL-C, was an independent predictor of the development of CVD especially in patients with T2DM. The aim of this study was to investigate the relationship between apoB and MetS in T2DM patients.

Methods: We analyzed 912 patients with T2DM. Fasting blood samples were taken for glycated hemoglobin, high-sensitivity C-reactive protein, total cholesterol, triglyceride (TG), high density lipoprotein cholesterol, LDL-C, and apoB. MetS was defined by the modified National Cholesterol Education Program Adult Treatment Panel III criteria. We performed a hierarchical regression analysis with apoB as the dependent variable. Age, sex, the number of components of MetS and LDL-C were entered at model 1, the use of lipid-lowering medications at model 2, and the individual components of MetS were added at model 3.

Results: Seventy percent of total subjects had MetS. ApoB level was higher in subjects with than those without MetS (104.5±53.3 mg/dL vs. 87.7±33.7 mg/dL, P<0.01) even after adjusting for LDL-C. ApoB and LDL-C were positively correlated to the number of MetS components. The hierarchical regression analysis showed that the increasing number of MetS components was associated with higher level of apoB at step 1 and step 2 (β=0.120, P<0.001 and β=0.110, P<0.001, respectively). At step 3, TG (β=0.116, P<0.001) and systolic blood pressure (β=0.099, P<0.05) were found to significantly contribute to apoB.

Conclusion: In patients with T2DM, apoB is significantly related to MetS independently of LDL-C level. Of the components of MetS, TG, and systolic blood pressure appeared to be determinants of apoB.

Keywords: Apolipoproetin B; Cardiovascular diseases; Diabetes mellitus, type 2; Metabolic syndrome.

Fig. 1. (A) Differences in low density lipoprotein cholesterol (LDL-C) and (B) apolipoprotein B (apoB) according to the presence of metabolic syndrome. Values are expressed as mean±SE. ^aAdjusted for LDL-C by analysis of covariance.

Fig. 2. (A) Differences in low density lipoprotein cholesterol (LDL-C) and (B) apolipoprotein B (apoB) according to the number of components of metabolic syndrome. Values are expressed as mean±SE. ANOVA, analysis of variance; P for trend, P value by the test for linear trend.