SEROLOGICAL STUDY FOR THE OCCURRENCE OF ANTIBODIES TO HUMAN GLUTAMIC-ACID DECARBOXYLASE IN PATIENTS WITH TYPE-I DIABETES-MELLITUS

Insulin-dependent diabetes mellitus (IDDM) seems to be marked by circu lating antibodies to a 64 kD islet cell autoantigen, identified as glu tamic acid decarboxylase (GAD). In our study we investigated the occur rence of CAD-antibodies by a commercially available ELISA in patients with recent onset of IDDM (n=18), subjects with longer duration of the disease (n=43), NIDDM patients (n=38), and a healthy control group (n =27). Anti-64: kD antibodies were absent in NIDDM and healthy control persons and present in 50% of recent onset IDDM patients and 21% of th e group with longer duration. Compared to other immunological paramete rs rue saw a minor relationship between CAD-antibody levels and islet cell antibody titers but no correlation with insulin autoantibody leve ls or HLA subtypes. A vague correlation seems to exist between serum l evels of GAD-antibodies and the duration of the disease, suggesting a loss of antigenic drive with the on-going destruction of pancreatic be ta-cells. We observed no association of elevated GAD antibody levels i n the later course of the disease with the development of the diabetic peripheral neuropathy, which is discussed controversially in the lite rature.