Lipophilic index of serum phospholipids in patients with type 2 diabetes and atherosclerotic cardiovascular disease: links with metabolic control, vascular inflammation and platelet activation.

Background: Little is known about the mechanisms underlying the association of the serum phospholipid lipophilic index (LI) with atherosclerotic cardiovascular disease (ASCVD) in patients with type 2 diabetes (T2D). Therefore, we investigated whether the LI is associated with glucometabolic control, meta-inflammation, thrombin generation, fibrin clot properties, endothelial function and platelet activation in T2D patients with angiographically documented ASCVD.

Methods: We studied 74 T2D patients with ASCVD, aged 65.6 ± 6.8 years, with a median diabetes duration of 10 years and median HbA1c of 7.0%. Serum phospholipid fatty acids (FAs) were measured by gas chromatography. The serum phospholipid LI was calculated as the sum of the products of the proportion (% of total FAs) with the melting points (°C) of each individual FA, divided by the sum of the proportions of all FAs. Levels of HbA1c, insulin, leptin, adiponectin, lipid profiles, inflammatory markers (hsCRP, interleukin-6, TNF-α), Lp-PLA₂ (a biomarker of vascular inflammation), endothelial function (sICAM-1, sVCAM-1, FMD, NMD), thrombin generation, fibrin clot properties and platelet activation, measured by light transmission aggregometry with arachidonic acid [AA] and adenosine diphosphate [ADP], were assessed.

Results: Patients with LI > 16.9 °C (median) had higher HbA1c concentrations by 5.9% compared to the remaining subjects (p = 0.035). In this group, HbA1c levels ≥ 7.0% were found more often than in individuals with LI ≤ 16.9 °C (62.2 vs. 35.1%; p = 0.020). Subjects with LI > 16.9 °C had higher levels of TCh by 17.1% (p = 0.012), LDL-Ch by 29.4% (p = 0.003), interleukin-6 by 22.2% (p = 0.031) and Lp-PLA₂ by 32.4% (p = 0.040), compared to the remaining patients. Moreover, they had increased maximal platelet aggregation induced by AA (p = 0.045), but not by ADP. Serum phospholipid LI correlated with HbA1c (r = 0.24; p = 0.037), TCh (r = 0.36; p = 0.002), LDL-Ch (r = 0.38; p < 0.001), interleukin-6 (r = 0.27; p = 0.020) and Lp-PLA₂ (r = 0.26; p = 0.026). There were no intergroup differences in endothelial function, thrombin generation and fibrin clot properties. Regression analysis showed that HbA1c ≥ 7.0% and serum levels of LDL-Ch, interleukin-6 and Lp-PLA₂ were predictors of LI > 16.9 °C in adjusted models.

Conclusions: In well-controlled T2D patients with ASCVD, the higher serum phospholipid LI is associated with worse glucometabolic control, enhanced vascular inflammation and higher platelet reactivity during aspirin treatment at cyclooxygenase-1-selective doses.