Autoantibodies against autonomic nervous tissues in type 2 diabetes mellitus: no association with cardiac autonomic dysfunction.

There is evidence that autoimmune factors contribute to the pathogenesis of cardiac autonomic dysfunction in Type 1 Diabetes mellitus (DM). To evaluate the presence of autoantibodies against autonomic nervous tissues in Type 2 DM, 127 patients were studied for complement-fixing sympathetic and parasympathetic ganglia (CF-SG and CF-PSG) autoantibodies with an indirect immunofluorescence technique. Five cardiac reflex tests were performed to investigate cardiac autonomic neuropathy. QTc interval was assessed in all patients. As a control group, 60 healthy non-diabetic subjects were also tested for CF-SG and CF-PSG autoantibodies. CF-SG autoantibodies were detected in 11 (9%) and CF-PSG autoantibodies were observed in 7 (6%) Type 2 DM patients, whereas in control subjects, the frequency was 1 (2%) and 0 (0%) respectively (ns vs. Type 2 DM patients). In Type 2 DM patients with cardiac autonomic neuropathy (n=31, 24%), CF-SG autoantibodies and CF-PSG autoantibodies were detected in 3 (10%) patients, respectively, compared to 8 (8%) and 4 (4%) in Type 2 DM patients without cardiac autonomic neuropathy (n=96, 76%, ns v. Type 2 DM with cardiac autonomic neuropathy). Both CF-SG autoantibodies and CF-PSG autoantibodies were observed in 2 (7%) Type 2 DM patients with cardiac autonomic neuropathy and 3 (3%) Type 2 DM patients without cardiac autonomic neuropathy. Type 2 DM patients with cardiac autonomic neuropathy demonstrated a longer QTc-interval (446+/-42 ms) than Type 2 DM patients without cardiac autonomic neuropathy (413+/-45 ms, p=0.0001). In Type 2 DM patients with a prolonged QTc-interval (>440 ms: n=29, 23%), 2 (7%) patients presented with CF-SG and 3 (10%) had CF-PSG autoantibodies. In Type 2 DM, CF-SG and CF-PSG autoantibodies are not frequently observed. The results do not give evidence, that immunological factors--like in Type 1 DM--play a role in the pathogenesis of cardiac autonomic dysfunction in Type 2 DM.

Scintigraphically assessed cardiac sympathetic dysinnervation in poorly controlled type 1 diabetes mellitus: one-year follow-up with improved metabolic control.

Diabetic neuropathy is thought to comprise a reversible metabolic and an irreversible structural component of neuronal abnormality. To study whether cardiac sympathetic dysinnervation in poorly controlled longer-term Type 1 Diabetes Mellitus (DM) without myocardial perfusion abnormalities is partially reversible with improved metabolic control, 123-I-metaiodobenzylguanidine (123-I-MIBG) scintigraphy (myocardial uptake score 1-6) was performed in 11 Type 1 DM patients (HbA1c 12.0 +/- 1.8%, duration of diabetes 10 +/- 4 yrs) one year after initial assessment. During follow-up, all patients had been treated with intensive insulin therapy and at one year, HbAlc had fallen to 8.4 +/- 1.4% (p < 0.01). The global myocardial 123-I-MIBG uptake score had improved in 5 patients at one year, remained unchanged in 5 patients, and deteriorated in 1 patient. Cardiac sympathetic dysinnervation (123-I-MIBG myocardial uptake (MU) score >2), initially observed in 10 patients, was detectable in 8 patients at follow-up. Myocardial uptake scores of the anterior, lateral, posterior, septal and apical region had improved in 6, 6, 6, 7 and 6 patients, but the mean changes of these scores did not reach significance. In patients with substantial improvement of metabolic control (HbAlc 7.3 +/- 0.6% at one year, mean HbA1c of months 2-12: 7.8%, n = 6), global myocardial uptake had improved from 4.3 +/- 1.0 to 3.2 +/- 1.0 (p < 0.05). Respectively, myocardial uptake score of the anterior, posterior and septal region had ameliorated: 3.8 +/- 1.3 vs 2.3 +/- 0.8 (p < 0.05), 4.0 +/- 1.7 vs 2.5 +/- 1.0 (p < 0.05), 4.3 +/- 1.2 vs 3.2 +/- 1.5 (p < 0.05). In conclusion, cardiac sympathetic dysinnervation in poorly controlled longer-term Type 1 DM patients is dominated by irreversible neuronal abnormalities. Substantial metabolic improvement, however, partially restores cardiac sympathetic dysinnervation, indicating the presence of a reversible component of cardiac sympathetic dysfunction in longer-term Type 1 DM.

Evidence for specific autoimmunity against sympathetic and parasympathetic nervous tissues in Type 1 diabetes mellitus and the relation to cardiac autonomic dysfunction.

There is growing evidence for the involvement of immunological factors in the pathogenesis of cardiac autonomic dysfunction in Type 1 diabetes mellitus (DM). To evaluate the presence of autoantibodies against autonomic nervous tissues and their relationship with tests of autonomic function, 64 newly diagnosed and 142 long duration Type 1 DM patients were investigated for sympathetic and parasympathetic ganglia (CF-SG and CF-PSG) autoantibodies with a complement-fixing indirect immunofluorescence technique. Five cardiac reflex tests were performed to assess autonomic function. Fifty-seven patients with neurological diseases other than diabetic neuropathy and 131 healthy control subjects were also tested for CF-SG and CF-PSG autoantibodies. CF-SG autoantibodies were observed in 47 (23%) and CF-PSG autoantibodies in 21 (10%) of 206 Type 1 DM patients (p < 0.001). In contrast, these autoantibodies were detected in 3 (5%) and 1 (2%) of patients with non-diabetic neurological diseases and 3 (2%) and 4 (3%) of control subjects (p < 0.01, p < 0.05, p < 0.0001, p < 0.05 vs Type 1 DM patients). All except two Type 1 DM patients with CF-PSG autoantibodies also presented with CF-SG autoantibodies. In diabetic patients with long duration, CF-SG autoantibodies were more frequent in patients with ECG-based cardiac autonomic neuropathy (CAN; > or =2 of 5 cardiac reflex tests abnormal) compared to patients without CAN although this did not reach statistical significance (29% vs 17%, p = 0.06). However, 4 (80%) of 5 newly diagnosed and 23 (32%) of 73 established Type 1 DM patients with abnormalities in heart rate variation during deep breathing and/or standing from lying presented with CF-SG autoantibodies compared to 12 (25%) of 58 newly diagnosed (p < 0.05) and 7 (11%) of 63 established Type 1 DM patients (p < 0.01), in whom both tests were normal. The results suggest that autoimmune factors contribute to the pathogenesis of cardiac autonomic dysfunction in Type 1 DM and that autoantibodies against sympathetic and parasympathetic nervous tissues are relatively specific for Type 1 DM.