Apolipoprotein(B) identifies dyslipidemic phenotypes associated with cardiovascular risk in normocholesterolemic type 2 diabetic patients

Abstract

Objective: Apolipoprotein(B) [apo(B)] reflects the total mass of atherogenic particles (VLDL, IDL, and LDL), and its increase is associated with cardiovascular disease independently of LDL cholesterol (LDLc) levels. Apo(B) determination has been recently standardized, but attention to regional reference limits is advisable. Our aim was to analyze the frequency of dyslipidemic phenotypes, including those dependent on increased apo(B) in normocholesterolemic type 2 diabetic patients.

Research design and methods: A total of 100 consecutively seen type 2 diabetic patients (63 men, 37 women; aged 59 +/- 11 years) were included, after excluding those on lipid-lowering therapy. Apo(B) cutoff (1.1 g/l) was obtained from a group of normolipidemic (47 men, 21 women) control subjects, and LDLc, triglycerides, and HDL cholesterol (HDLc) cutoff points were those from the National Cholesterol Education Program guidelines. LDLc levels were obtained by ultracentrifugation if triglyceride levels were > 3.45 mmol/l; otherwise, they were calculated (Friedwald). Apo(B) levels were measured by immunoturbidimetry.

Results: Normocholesterolemia (LDLc < 4.13 mmol/l) appeared in 75 of the 100 patients, of whom 55 were normo- and 20 hypertriglyceridemic. Hyperapolipoprotein(B) [hyperapo(B)] was the most frequent lipid disorder, present in 34 (45%) of the normocholesterolemic patients (22 normo- and 12 hypertriglyceridemic). Low HDLc levels were more prevalent (53%) in patients with hyperapo(B) than in the rest (24%).

Conclusions: Hyperapo(B) was found in almost half of the normocholesterolemic type 2 diabetic patients and was frequently associated with low HDLc levels and hypertriglyceridemia. Thus, given its independent association with cardiovascular disease and that it identifies high-risk phenotypes in normocholesterolemic diabetic patients apo(B) should be used to evaluate the lipidic pattern of these patients.