Hello Sgtmajor, and welcome to the community!
American Standard does make a insulated toilet tank, it the Renaissance II model # 741DA.151.020, and you can check with your local Home Depot to see if they carry it or you can order it.
Keep in mind, your toilet can still sweat if the incoming water is very cold and the room humidity is very high. The most effective (and expensive) approach is to install a mixing valve that's connected to a hot-water pipe. Warming the incoming water slightly stops condensation completely, but there are some downsides. For one thing, you'll be flushing water you paid dearly to heat down the drain. For another, it's often difficult to install the valve in a location that only affects the toilet — you don't want warm water coming out of cold-water faucets, too. These valves are much easier to install during new construction.
Angelo