Impact of disease duration on cardiovascular and pupillary autonomic nervous function in IDDM and NIDDM patients

To determine the age-independent impact of disease duration on autonomic nervous function in diabetic patients and to compare it with other disease-related complications.

Of the patients with diabetes, 166 (66 IDDM, 100 NIDDM) were investigated using standardized cardiovascular and pupillary test procedures, which provide 10 age-independent percentile values for each patient. Sensorimotor neuropathy was assessed using a standardized clinical examination, retinopathy by fundoscopy, and nephropathy using daily urinary protein excretion and creatinine clearance.

The duration of the disease did not correlate with the results of any one of six standard cardiovascular tests (P > 0.15). Pupillary parameters showed a weak negative correlation with disease duration (P < 0.04). Prevalence of cardiovascular autonomic dysfunction was not different in five different subgroups subdivided according to disease duration (0-6, 7-12, 13-18, 19-24, and > or = 25 years), whereas prevalence of pupillary dysfunction changed significantly with disease duration (P = 0.016). In contrast, the prevalence of sensorimotor neuropathy (P = 0.006), retinopathy (P < 0.001), and proteinuria (P = 0.010) was significantly higher in patients with long-standing disease. Disease duration was not significantly different in patients without overall cardiovascular dysfunction, as compared with patients with dysfunction (15.6 +/- 1.0 vs. 16.5 +/- 1.5 years, P = 0.626). This was also found when considering overall pupillary dysfunction (14.5 +/- 1.4 vs. 17.2 +/- 1.0 years, P = 0.125).

Disease duration was not correlated with cardiovascular autonomic nervous function, whereas a correlation was observed with pupillary autonomic nervous function, sensorimotor neuropathy, retinopathy, and proteinuria. This may indicate that cardiovascular autonomic nervous function does not markedly change during the course of the disease. The question arises whether cardiovascular autonomic neuropathy may be more a functional abnormality than a structural lesion of the autonomic nervous system, which may be already present at the beginning, or even before, the manifestation of diabetes.