I think flat bush is another name for ketosis-prone diabetes. Not sure about the differential bit or why it mentions Type 1.
You and I both probably need to observe the city limits then, Mike - you the Bristol ones and me the Coventry ........ Oh hang on, nut ones, not flat ......Ah! Thanks @Inka - never even heard of flatbush as a diabetes term.
Though I now have a Tina Turner ear worm going round in my head!