A medical device, such as a medical wire, which includes a coating applied to the surface of the medical wire. The coating includes a base layer bonded to the surface of the medical wire and an at least partially transparent low-friction top coat applied to the base layer. The base layer includes heat activated pigments that change color when heated above a color shifting temperature. In one embodiment, the color of the pigment in one area contrasts with the color of the pigment in an adjacent area without otherwise affecting the low-friction surface of the coating. The areas of different color created in locations along the length of the low-friction coated medical wire form markings which, as an example, enable a surgeon to determine the length of the medical wire inserted into a body by observing the markings on the portion of the marked medical wire located exterior to the body.