Well, yes and no.

186,282 miles per hour is the speed of light in a vacuum. Glass has a "refractive index" of some number because it's not a vacuum and the ability of glass tubing to conduct light is due to the fact that attenuated light tends to bounce off the walls of the fiber like mirrors, increasing the relative distance the light must travel. Single mode fiber has a refractive index of around 1.467, although a number of factors too numerous to go into here affect this number, but it's a general "rule of thumb". Take 186,282 and divide by the refractive index (1.467) and you get the speed at which light travels through fiber optic cabling, or 124,188 miles per hour.