The pathological mechanism of left carotid plaque formation is the formation of plaque after hardening of the carotid artery wall. The causes can be: 1, abnormal lipid metabolism, the increase of LDL cholesterol, very low density lipoprotein cholesterol, total cholesterol will lead to the hardening of the arterial wall and the formation of plaque; 2, smoking history, long-term smoking patients will also arterial wall hardening; 3, hypertension disease, patients suffering from hypertension disease, long-term poor blood pressure control, poor hemodynamics, resulting in the decline of vascular function, plaque formation; 4, diabetes mellitus , some studies have shown that abnormal lipid metabolism is related to insulin resistance, which may be causal with diabetes.