Data produced by an electron cyclotron interferometer diagnostic are now available to the real-time control systems of of the joint European torus (JET) tokamak. The data consist of absolutely calibrated electron temperature profiles, covering the plasma low-field side, core and part of the high-field side, for most of the range of magnetic fields used at JET. The profiles are obtained without the need for real-time equilibrium reconstructions. A simple and robust metric for the peakedness of the profiles was defined and employed in a real-time control system. The main goal was to identify discharges at risk of disruption, after impurity accumulation in the core, and terminate them safely. This was successfully tested on the current ramp-up phase of hybrid plasmas, developed in support of high-performance scenarios for the upcoming deuterium-tritium JET campaign.