RBP4 and hypertensive disorder: Increasing evidence suggests that RBP4 induces insulin resistance (IR) (9, 10) and is closely associated with diabetes mellitus (DM) (11, 12), obesity (13), metabolic syndrome (MS) (14, 15), hyperuricaemia (HUA) (16, 17), non-alcoholic fatty liver disease (NAFLD) (18, 19), hypertension (HTN) (20, 21), and cardiovascular diseases (CAD) (22).