The lack of anti-idiotypic antibodies, not the presence of the corresponding autoantibodies to glutamate decarboxylase, defines type 1 diabetes.
Oak S, Gilliam LK, Landin-Olsson M, Törn C, Kockum I, Pennington CR, Rowley MJ, Christie MR, Banga JP, Hampe CS. Proc Natl Acad Sci U S A. 2008 Apr 8; 105(14):5471-6. Epub 2008 Mar 26.