A method for manufacturing a glass body for a potentiometric sensor, including: loading a first spindle of a glass lathe with outer and inner glass tubes, so that the glass tubes are arranged coaxially with one another and with the axis of rotation of the first spindle, the inner glass tube and the outer glass tube each has a media-side end, and the two media-side ends have defined axial positions relative to one another; loading a second spindle with an auxiliary glass tube, so that the axis of rotation of the second spindle is arranged coaxially with the axis of rotation of the first spindle; moving the auxiliary glass tube to be contiguous with the outer glass tube; fusion joining of the outer glass tube with the auxiliary glass tube; producing a connection between the outer glass tube, or the auxiliary glass tube, and the inner glass tube; removing a remainder of the auxiliary glass tube; producing a media-side opening of the inner glass tube; and forming a media-side edge of the opening. Optionally, the method includes, additionally, the automatic blowing of a glass membrane on the media-side edge.