Soluble urokinase plasminogen activator receptor, platelet aggregation, and carotid plaque thickness in diabetes: A cross-sectional analysis

Background: Soluble urokinase plasminogen activator receptor (suPAR) is an inflammatory biomarker strongly linked with cardiovascular disease in diabetes. By investigating its association with platelet aggregation levels and carotid plaque thickness, we can potentially improve the characterization of cardiovascular pathophysiology in type 1 (T1D) and type 2 diabetes (T2D).Methods: SuPAR was measured post-hoc in plasma collected in two cross-sectional studies including 1) in-dividuals with T1D and 2) individuals with T2D without known cardiovascular disease. Platelet aggregation was analyzed employing impedance aggregometry using the agonists arachidonic acid (ASPI), adenosine diphosphate (ADP), and thrombin receptor activating peptide-6 (TRAP). Carotid plaque thickness was assessed bilaterally, and the thickest plaque (cPTmax) was analyzed. Correlations and associations of suPAR with platelet aggregation and cPTmax were assessed with Pearson's R and linear regressions adjusted for sex, age, C-reactive protein, estimated glomerular filtration rate, and platelet levels (only for aggregation analysis). ASPI analyses were only performed in participant not receiving aspirin treatment. Standardized estimates with 95 % confidence intervals are presented.Results: Two-hundred eighty-three with T1D (mean age 55 years, 44 % women) and 493 individuals with T2D (mean age 65 years, 33 % women) were included. SuPAR levels were positively correlated to platelet aggregation in both T1D (ADP: R = 0.18, p = 0.003; ASPI R = 0.13, p = 0.026) and T2D (ADP R = 0.14, p = 0.002; ASPI R = 0.14, p = 0.017). In adjusted linear regressions higher SuPAR levels were associated with higher ADP induced platelet aggregation in both T1D (26 (8, 44) AU/min, p = 0.004) and T2D (22 (3, 42) AU/min, p = 0.025), while associations to the other agonists were not conclusive. Higher suPAR levels were associated with thicker cPTmax in T1D (0.19 (0.07, 0.32) mm, p = 0.003), but not in T2D (p = 0.94).Conclusion: Higher levels of suPAR, an inflammatory generalized disease biomarker, were associated with increased platelet aggregation and thicker cPTmax, in type 1 diabetes. Similar associations with platelet ag-gregation were found in type 2 diabetes, but not for carotid plaque thickness. These results suggest distinct cardiovascular pathomechanisms in T1D and T2D, although prospective studies are needed to confirm these findings.