Nonlinear association between high-density lipoprotein cholesterol and carotid atherosclerosis risk in patients with type 2 diabetes: a retrospective analysis from China

OBJECTIVE: The objective of this study was to evaluate the effect of high-density lipoprotein cholesterol (HDL-C) on carotid atherosclerosis (CAS) risk in patients with type 2 diabetes. METHODS: This retrospective cohort study included 390 patients with type 2 diabetes hospitalized in medical institutions between January 2023 and March 2024. Multivariate logistic regression models were used to evaluate the effect of HDL-C on CAS. Nonlinear associations were examined using restricted cubic spline models. RESULTS: The cohort demonstrated a CAS incidence of 66.41% (95% CI 61.70-71.12%). Multivariate regression demonstrated that higher HDL-C concentrations were associated with a lower risk of CAS (adjusted OR = 0.27, 95% CI 0.09-0.80, P = 0.0187). Notably, an L-shaped relationship was identified, with a threshold effect; a significant reduction in CAS risk was observed for HDL-C levels ≤ 1.62 mmol/L (adjusted OR = 0.10, 95% CI 0.03-0.42, P = 0.0014), while no significant association was detected above this level (adjusted OR = 5.34, 95% CI 0.25-114.45, P = 0.2844). CONCLUSION: Our findings unveil an L-shaped correlation between HDL-C and CAS risk, with a distinct protective effect of HDL-C observed only below the inflection point. Our findings suggest the potential value of clinical trials aiming to elevate HDL-C as a therapeutic strategy for controlling CAS.