LDL and ApoB 

While LDL estimates the amount of cholesterol carried within LDL particles, apoB reflects the total number of atherogenic lipoproteins and provides a more direct measure of the number of atherogenic particles in circulation.

Each atherogenic particle, including LDL, very-low-density lipoprotein (VLDL), intermediate-density lipoprotein, and Lp(a), contains a single apoB molecule,1 meaning apoB serves as a one-to-one marker of total particle number.4

In contrast, LDL particles vary in size and composition. Larger LDL particles tend to carry more cholesterol, while smaller, denser LDL particles carry less cholesterol per particle but are considered more atherogenic. These small, dense LDL particles easily penetrate the arterial wall, are more susceptible to oxidation, and have a longer circulating half-life, all of which increase their potential to promote atherosclerosis.5

An individual may have an LDL value at goal yet still have a high number of small, dense LDL particles and higher cardiovascular risk. This discordance is more common in individuals with ASCVD, cardiometabolic kidney syndrome, elevated triglycerides (>150 mg/dL), or diabetes.

In these cases, apoB can provide better insight into individual risk and therapeutic guidance. A higher particle number is strongly associated with an increased risk of myocardial infarction and other ASCVD events.

ApoB goals for individuals with diabetes are stratified as follows:

• < 90 mg/dL 
• < 70 mg/dL with ASCVD or diabetes-specific risk factors.
• In the presence of subclinical or clinical atherosclerosis, the target is lowered to <55 mg/dL.