Discordance between apolipoprotein B and low-density lipoprotein particle number is associated with insulin resistance in clinical practice.

•Discordance between apolipoprotein B (apoB) and low-density lipoprotein (LDL) particle number by nuclear magnetic resonance spectroscopy in routine clinical practice is more widespread than currently recognized.•In a large cohort of patients (N = 412,013), discordance (LDL particle concentration [LDL-P] > ApoB) was associated with smaller LDL particle sizes and hyperinsulinemia, whereas discordance (ApoB > LDL-P) was associated with elevated levels of lipoprotein (a).•In a smaller group of well-characterized patients (N = 1411), similar patterns were observed, and discordance (LDL-P > ApoB) was also associated with higher rates of statin use.