Cold pressor test in diabetic autonomic neuropathy.

The tests for evaluating sympathetic dysfunction seen in diabetic patients are few and insensitive. For this reason, there are some difficulties in diagnosing sympathetic dysfunction and additional tests are required. The cold pressor test causes a strong sympathetic stimulus and this study investigated whether this test could be helpful in diagnosing sympathetic dysfunction. The cold pressor test was applied to a group of diabetic patients (n = 33) and a control group (n = 15). The mean systolic cold pressor response in diabetic patients was found similar to controls (9 +/- 1.4 vs. 10.6 +/- 1.2 mmHg). However the mean diastolic cold pressor response was significantly lower in diabetic patients as compared with the control group (7.7 +/- 1.0 vs. 12.0 +/- 1.1 mmHg, P < 0.05). Cardiovascular reflex tests were also applied to diabetic patients and deep breathing and orthostatic hypotension test results were used to categorize the patients with parasympathetic and/or sympathetic dysfunction. In patients with autonomic neuropathy the diastolic cold pressor response was smaller than the controls (6.9 +/- 1.3 vs. 12.0 +/- 1.1 mmHg, P < 0.05); however, in patients without autonomic neuropathy it was not significantly different from controls (8.7 +/- 1.8 vs. 12.0 +/- 1.1). The systolic cold pressor test results showed no difference between patients with or without parasympathetic dysfunction but diastolic cold pressor results in patients with sympathetic dysfunction were significantly lower than the results of the patients without sympathetic dysfunction (3.8 +/- 1.3 vs. 9.1 +/- 1.3 mmHg, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)