Bojanin D, et al. - In this cross-sectional study performed on 207 patients with type 1 diabetes mellitus (T1DM) (106 boys and 101 girls), aged 13.9 ± 3.0 years and treated by intensive insulin therapy, researchers examined the link between proprotein convertase subtilisin/kexin 9 (PCSK9) and lipoprotein subclasses, with respect to glycemic control. According to findings, the association between PCSK9 and lipoprotein subclasses in T1DM was altered by the extent of achieved metabolic control. Worsening of glycemic control was accompanied by a significant increase in plasma PCSK9 levels. The highest proportion of small, dense low-density lipoprotein (sdLDL) and smaller high-density lipoprotein (HDL) particles were seen among T1DM patients with poor glucoregulation. Only in those with suboptimal/poor glucoregulation, a positive association was seen between PCSK9 and markers of glucose homeostasis and serum lipid parameters. Also, an inverse association of plasma PCSK9 level with a relative proportion of sdLDL particles was seen in well-controlled T1DM; The significance of this link was reported in multivariate analysis. A positive association of PCSK9 with the proportion of the smallest HDL3c particles as well as negative association with HDL size was observed in T1DM patients with suboptimal/poor glycemic control.