Introduction:
Accumulating evidence suggests that apolipoprotein B (apoB) is superior to low-density lipoprotein cholesterol (LDL-C) in prediction of cardiovascular events. Yet, an important outstanding question is whether apoB, relative to LDL, is an enhanced marker for subclinical atherosclerosis, particularly in diabetics where LDL levels may underestimate atherogenic lipid burden due to increased proportion of small, dense LDL.
Hypothesis:
We hypothesized that plasma apoB would be a better predictor than LDL-C of coronary artery calcification (CAC) scores in type 2 diabetics and non-type 2 diabetics.
Methods:
We performed cross-sectional analyses of asymptomatic Caucasians in (1) The Study of Inherited Risk of Coronary Atherosclerosis (434 men and 383 women; median age 48, non-diabetics) and (2) The Penn Diabetes Heart Study (580 men and 261 women; median age 60, type 2 diabetics).
Results:
Levels of apoB and LDL-C were correlated in diabetics (r=0.78, p<0.001) and non-diabetics (r=0.77, p<0.001). There was no association between LDL-C and CAC in diabetics. In non-diabetics, an association of LDL-C was lost after adjustment for total cholesterol. In contrast, after controlling for age, gender, statin therapy, and total cholesterol, levels of apoB were positively associated with CAC in diabetics [tobit regression ratio for 30 mg/dl increase in apoB 2.94 (95% CI 1.62 – 5.53), p=0.001) and had a more modest association with CAC in non-diabetics [1.67 (95% CI 1.16 – 2.32), p=0.005].
Conclusions:
ApoB, but not LDL-C, predicted CAC scores, a measure of coronary atherosclerotic burden. The strength of this association was greater in diabetics than non-diabetics. Relative to LDL-C, plasma apoB levels may be particularly useful in assessing CVD risk in type 2 diabetes.
Low Levels of Low-Density Lipoprotein Cholesterol and Blood Pressure and Progression of Coronary Atherosclerosis
