A regulating valve of the type preferably used for dynamic regulation of fluid-borne systems, such as central heating systems in housing and industrial buildings or cooling facilities, where the control valve is provided with a valve housing with an inlet and an outlet, where a valve insert with an orifice is provided in the valve housing by which the flow in the regulating valve can be regulated, and where additionally there are detectors for detecting either supply pressure or discharge pressure and another pressure, respectively. The regulating valve is provided with a modular valve insert which at least includes a differential pressure regulator, a venturi, a throttle device and a coupling member for an actuator, where the various modules have interacting joining means. A valve insert may thus be built up of respective modules, where the modules are selected individually with the most suitable specifications for the individual task. It is thus not required to make as many different combinations of valve inserts since they are combined modularly according to need.