Hypertriglyceridemic hyperapoB in type 2 diabetes

Abstract

OBJECTIVE - Much less attention has been paid to LDL in type 2 diabetes than to VLDL or HDL. In particular, there are few data on apoB levels in these patients. Moreover, most reports have focused on mean lipoprotein levels and consequently there is little information on the frequencies of the various dyslipidemic phenotypes. RESEARCH DESIGN AND METHODS - Plasma and lipoprotein lipids, apoB and apoA1 were measured by standardized methods. LDL particle size was determined by PAGE. The total cohort was divided into phenotypes by two different methods. The first was based on triglycerides (≤ or <1.5 mmol/l) and LDL cholesterol (≤ or <4 mmol/l), whereas the second was based on triglycerides (≤ or <1.5 mmol/l) and apoB (≤ or <120 mg/dl). RESULTS - For the overall cohort, plasma triglycerides were elevated (2.13 ± 1.6 mmol/l), total and LDL cholesterol were normal (5.34 ± 1.1 and 3.28 ± 0.88 mmol/1, respectively), and peak LDL size was reduced (252.9 ± 5.8 Å). HDL cholesterol was between the 25th and 50th percentiles of the general population (1.12 ± 0.36 mmol/1). The average level of apoB was 114 ± 29 mg/dl, a value that is between the 50th and 75th percentiles of the general population and is higher than that for LDL cholesterol, which was between the 25th and the 50th percentiles of the population. The results of the phenotyping analysis were as follows. Using the conventional approach, only 23% has abnormal LDL, i.e., an elevated LDL cholesterol level. Using the new approach, almost 40% has an elevated apoB and therefore an elevated LDL particle number. Only 12.8% has combined hyperlipidemia based on the conventional approach, whereas almost one-third had the equivalent, hypertriglyceridemic hyperapoB-based on the new algorithm. The severity of the dyslipoproteinemia in this group was noteworthy. Although the average LDL cholesterol was 3.91 mmol/l, a value just below the 75th percentile of the general population, the average apoB was 145 mg/dl, a value that approximates the 95th percentile of the population. CONCLUSIONS - The dyslipidemic profile of patients with type 2 diabetes is not uniform. A substantial group have normal lipids and normal LDL particle number and size whereas others have markedly abnormal profiles. Diagnosis based on triglycerides and apoB rather than triglycerides and LDL cholesterol revealed that more than one in five had hypertriglyceridemic hyperapoB, which is characterized by hypertriglyceridemia, marked elevation of LDL particle number, small dense LDL, and low HDL, a constellation of abnormalities that is associated with markedly accelerated atherogenesis and therefore justifies intensive medical therapy.