Existing research has shown that retinol binding protein(RBP4) has an impairing effect on arterial elasticity and induces insulinresistance, but the clinical value of RBP4 in patients with coronary heartdisease (CHD) combined with type 2 diabetes mellitus (T2DM) has not beeninvestigated. This evidence concerns the gene RBP4 and diabetes mellitus.