AUTOANTIBODIES TO SYMPATHETIC-GANGLIA, GAD, OR TYROSINE PHOSPHATASE IN LONG-TERM IDDM WITH AND WITHOUT ECG-BASED CARDIAC AUTONOMIC NEUROPATHY

OBJECTIVE - To evaluate the association of autoantibodies to complemen t-fixing sympathetic ganglia (CF-SG), GAD, and tyrosine phosphatase (I A-2) with electrocardiogram (ECG)based cardiac autonomic neuropathy (C AN) in long-term IDDM. RESEARCH DESIGN AND METHODS - We examined the p revalence of autoantibodies to CF-SG (by complement-fixing indirect im munofluorescence), GAD, and IA-2 (by radioligand assay) and islet cell s (by indirect immunofluorescence) in 96 long-term IDDM patients (41 w ith EGG-based CAN, greater than or equal to 2 of 5 cardiac reflex test s abnormal; 55 without ECG-based CAN). As a control group, 89 healthy nondiabetic subjects were investigated. RESULTS - CF-SG autoantibodies were observed more frequently in long-term IDDM patients than in the control group (25 vs. 4%, P = 0.0001). Of the IDDM patients, 14 (34%) with CAN and 10 (18%) without CAN presented with CF-SG autoantibodies (P = 0.06). GAD or IA-2 autoantibodies were detected in 14 (34%) and 1 7 (41%) IDDM patients with CAN, compared with 24 (44%) and 29 (53%) ID DM patients without CAN (P = 0.2, P = 0.2). Islet cell antibodies were observed in 6 (15%) IDDM patients with and in 9 (16%) IDDM patients w ithout CAN (P = 0.5). CONCLUSIONS - In long-term IDDM, the role of CF- SG autoantibodies, which tend to be more frequent in patients with EGG -based CAN, requires further investigations. The persistence of GAD an d IA-2 autoantibodies is not related to EGG-based CAN.