No luck with Medicare. I've been told by both Dexcom and MiniMed that it's not covered.
And most Medicare supplement coverage simply says that if Medicare denies it, then they'll deny it. If anyone hears of any that will cover CGM, holler!
Be sure to talk to the CGM manufacturer and let them know that you are on Medicare -- they quoted me a price that is below MSRP both for the device and for the sensors.