BACKGROUND: Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) levels have been suggested as novel atherosclerotic biomarker. PCSK9 plays important roles in the pathogenesis of atherosclerosis by regulating the degradation of low-density lipoprotein receptor as well as different inflammatory pathways. Considering the important prognostic role of arterial stiffness in cardiovascular disease (CVD), the aim of the study is to investigate the correlation between PCSK9 levels and arterial stiffness in a cohort of diabetic patients, without previous CV events. METHODS: This cross-sectional analysis enrolled 401 Caucasian patients with type II diabetes mellitus (T2DM). PCSK9 levels were measured by ELISA test, arterial stiffness was estimated by measuring carotid-femoral pulse wave velocity (PWV). RESULTS: Patients were divided in three tertiles according to increasing value of PCSK9. From the I to the III tertiles, there was a significant increase in high sensitivity C-reactive protein (hs-CRP), fibrinogen and white blood cells (WBC) and a reduction in estimated glomerular filtration rate (e-GFR). Patients with higher levels of PCSK9 presented increased systolic, diastolic blood pressure, pulse pressure and PWV. PWV was significantly and directly correlated with PCSK9, fibrinogen, age, BMI and PP, and indirectly correlated with diet, lifestyle and e-GFR. Serum PCSK9 was the major predictor of PWV, justifying a 16.9% of its variation. CONCLUSION: Our study demonstrates a close association between circulating PCSK9 levels and PWV in T2DM subjects without previous CV events even after adjusting for well-known CV risk factor and pharmacological medications. Serum PCSK9 could be a useful biomarker for CV risk stratification in diabetic subjects.