Association between proprotein convertase subtilisin/kexin 9 (PCSK9) and lipoprotein subclasses in children with type 1 diabetes mellitus: Effects of glycemic control

Background and aims: Dyslipidemia in type 1 diabetes mellitus (T1DM) is characterised by altered distributions of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subclasses. Recent studies suggested that proprotein convertase subtilisin/kexin 9 (PCSK9) may contribute to the development of dyslipidemia in T1DM. In this cross-sectional study, we investigated the association between PCSK9 and lipoprotein subclasses in young T1DM patients, with respect to glycemic control. Methods: Plasma PCSK9 and lipoprotein subclasses were determined in 207 patients with T1DM (106 boys and 101 girls), aged 13.9 +/- 3.0 years and treated by intensive insulin therapy. Results: Plasma PCSK9 levels significantly increased with worsening of glycemic control (p < 0.001). T1DM patients with poor glucoregulation had the highest proportion of small, dense LDL (sdLDL) and smaller HDL particles, as well. PCSK9 was positively associated with markers of glucose homeostasis and serum lipid parameters only in patients with suboptimal/poor glucoregulation. In well-controlled T1DM, plasma PCSK9 level was inversely associated with a relative proportion of sdLDL particles (p < 0.01) and this association remained significant in multivariate analysis. In T1DM patients with suboptimal/poor glycemic control, PCSK9 was positively associated with the proportion of the smallest HDL3c particles (p < 0.001), but negatively with HDL size (p < 0.05). Conclusions: The extent of achieved metabolic control modifies the association between PCSK9 and lipoprotein subclasses in T1DM. Further investigations are needed to reveal whether the observed effects of glycemic control on PCSK9 and sdLDL levels have causal consequences on CVD risk in young patients with T1DM.