Unfortunately, Diesel lost his battle with liver disease.  Diesel was one of those cats that was known to many of the volunteers at the shelter because he always managed to be in all of the rooms upstairs.  You could not open a door upstairs without him running thru it.  Although running from room to room was one of his favorite things, his most favorite thing to do was lay in your lap for hours to be pet.  He would grab your arm if you stopped petting him.  He will be sorely missed by all of us.