Page 60 of this states that Imperial Guard Medical Attendants (male nurses) wore the uniform of the Guard Administration, entirely grey/blue with red trim.
However, Line Medical Attendants wore a quite different uniform of brown jackets faced with red, as shown on Page 62 of Elting's "Napoleonic Uniforms - Volume II" and also on Page 79 of Funken's "Arms and Uniforms of the Napoleonic Wars - Part 1".
What did intrigue me however is that the Histoire & Colletions book does have an illustration on Page 59 of an actual uniform coat which is preserved in a museum in Holland. This is brown with crimson facings and Imperial Guard Medical Service buttons, in other words it is in a similar colour scheme to the line medical services. Does this imply that perhaps Imperial Guard medical attendants in fact wore brown and not blue/grey?
Rod