NOUN (1)

1. someone who has diabetes;


ADJECTIVE (2)

1. of or relating to or causing diabetes;

2. suffering from diabetes;

The Collaborative International Dictionary of English v.0.48:

Diabetic \Di`a*bet"ic\, Diabetical \Di`a*bet"ic*al\, a.
   Pertaining to diabetes; as, diabetic or diabetical treatment.
   --Quian.
   [1913 Webster]

   Diabetic sugar. (Chem.) Same as Dextrose. Diablerie

WordNet (r) 3.0 (2006):

diabetic
    adj 1: of or relating to or causing diabetes
    2: suffering from diabetes
    n 1: someone who has diabetes