AGT and diabetes mellitus: Diabetes and their associated diseases are linked with the propagation of vascular smooth muscle cells, whereas thymoquinone dose‐dependently prevented rats from these complications through multiple mechanisms such as inhibition of cyclin D1 expression, angiotensin II (Ang II)‐induced VSMCs' cell cycle progression, alteration in p21 expression, reduction in MMP‐9 expression, ROS production, and NADPH oxidase activity, and enhancement in superoxide dismutase activity.