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 complement fixing sympathetic ganglia (CF-SG), GAD, and tyrosine phosphatase (IA-2) with electrocardiogram (ECG)-based cardiac autonomic neuropathy (CAN) in long- term IDDM. RESEARCH DESIGN AND METHODS - We examined the prevalence of autoantibodies to CF-SG (by complement-fixing indirect immunofluorescence), GAD, and IA-2 (by radioligand assay) and islet cells (by indirect immunofluorescence) in 96 long-term IDDM patients (41 with ECG-based CAN. ≤2 of 5 cardiac reflex tests 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 17 (41%) IDDM patients with CAN, compared with 24 (44%) and 29 (53%) IDDM 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 without CAN (P = 0.5). CONCLUSIONS - In long-term IDDM, the role of CF-SG autoantibodies, which tend to be more frequent in patients with ECG-based CAN, requires further investigations. The persistence of GAD and IA-2 autoantibodies is not related to ECG-based CAN.