HDL cholesterol as a residual risk factor for vascular events and all cause mortality in patients with type 2 diabetes

Abstract

OBJECTIVE: To evaluate whether low HDL cholesterol (HDL-c) levels are a risk factor for cardiovascular disease and mortality in patients with type 2 diabetes and whether it remains a residual risk factor when attaining low LDL cholesterol (LDL-c) treatment goals or when LDL-c is treated with intensive lipid-lowering therapy. RESEARCH DESIGN AND METHODS: We performed a prospective cohort study of 1,829 patients with type 2 diabetes included in the Second Manifestations of ARTerial disease (SMART) cohort. Cox proportional hazard models were used to evaluate the risk of HDL-c on cardiovascular events and all-cause mortality. Analyses were performed in strata of LDL-c levels (<2.0, 2.0-2.5, and >2.5 mmol/L) and lipid-lowering therapy intensity and were adjusted for age, sex, BMI, smoking, alcohol, LDL-c, triglycerides, systolic blood pressure, estimated glomerular filtration rate, glucose, and HbA1c. RESULTS: A total of 335 new cardiovascular events and 385 deaths occurred during a median follow-up of 7.0 years (interquartile range 3.9-10.4). No relation was found between plasma HDL-c and cardiovascular events (hazard ratio [HR] 0.97, 95% CI 0.93-1.01) or all-cause mortality (HR 0.99, 95% CI 0.96-1.03). Subgroup analysis supported effect modification by plasma LDL-c levels. In patients with LDL-c levels <2.0 mmol/L, higher HDL-c was related to higher risk for all-cause mortality (HR 1.14, 95% CI 1.07-1.21). Higher HDL-c was also related to higher risk for cardiovascular events in patients with LDL-c levels <2.0 mmol/L (HR 1.10, 95% CI 1.07-1.21) in contrast to patients with LDL-c levels between 2.0 and 2.5 mmol/L (HR 0.85, 95% CI 0.75-0.95) and >2.5 mmol/L (HR 0.96, 95% CI 0.91-1.00). CONCLUSIONS: In high-risk patients with type 2 diabetes with LDL-c levels <2.0 mmol/L, higher HDL-c at baseline is unexpectedly related to a higher risk for cardiovascular events and all-cause mortality in contrast to high-risk patients with type 2 diabetes with LDL-c levels between 2.0 and 2.5 mmol/L.