AUTOANTIBODIES TO GLUTAMIC-ACID DECARBOXYLASE (GAD), 64000-MR ISLET-CELL PROTEIN (64K) ANTIBODIES AND ISLET-CELL ANTIBODIES (ICA) IN INSULIN-DEPENDENT DIABETES-MELLITUS WITH AND WITHOUT AUTOIMMUNE-DISEASES IN JAPAN

IDDM is known to be a heterogeneous disease which is frequently compli cated with other autoimmune diseases (AID). We previously reported tha t IDDM patients with AID: were characterized by late onset of diabetes , persistent ICA-positivity and increased association with DR9, while those without AID were characterized by rapid decline of ICA with dura tion of diabetes and increased association with DR4. The present study was performed to investigate the prevalence of autoantibodies to glut amic acid decarboxylase (GAD), autoantibodies to 64KDa islet cell prot ein (64K antibodies) and islet cell antibodies (ICA) in Japanese IDDM patients with and without AID. In short-duration diabetes (<1 year), t he prevalence of GAD antibodies, 64K antibodies and ICA were 100%, 100 %, and 100%, respectively, in IDDM patients with AID, and 82%, 64% and 82%, respectively, in patients without AID. In long-standing diabetes (3-28 years), the prevalence of GAD antibodies were 76%, 48% and 33%, respectively, in IDDM patients with AID, and 48%, 28% and 16%, respec tively, in patients without AID. The mean levels of GAD antibodies, 64 K antibodies and ICA in IDDM patients with AID was significantly highe r than in those without AID. Furthermore, the prevalence of GAD antibo dies were detected more frequently than ICA and 64K antibodies in long standing IDDM patients. Our results demonstrate that the prevalence o f GAD antibodies in IDDM patients were as high as those reported in Ca ucasians, and high levels of GAD antibodies were observed in IDDM pati ents with AID.