Medical devices and methods for making and using medical devices are disclosed. An example medical device may include a guide extension catheter. The guide extension catheter may include a push member having a proximal portion with a proximal stiffness, a distal portion with a distal stiffness different from the proximal stiffness, and a transition portion disposed between the proximal portion and the distal portion. The transition portion may provide a smooth transition between the proximal stiffness and the distal stiffness. The push member may have a first outer diameter. A distal tubular member may be attached to the push member. The distal tubular member may have a second outer diameter larger than the first outer diameter.