Cardiac and plasma catecholamine responses to exercise in patients with type 2 diabetes: Prognostic implications for cardiac-cerebrovascular events

Background: Patients with diabetes mellitus have an altered exercise plasma catecholamine response, which may be related to the abnormal sympathoadren al function and autonomic neuropathy. Presence of autonomic neuropathy is a ssociated with poor prognosis, but relationship between exercise plasma cat echolamine and prognosis has not been investigated. This study determined i f altered plasma catecholamine response to exercise was associated with car diac-cerebrovascular events. Methods: Forty patients with type 2 diabetes w ithout apparent macrovascular complications and 30 control subjects perform ed treadmill exercise with serial measurements of plasma norepinephrine and epinephrine. Clinical, exercise, and catecholaminergic variables considere d relevant to the cardiac-cerebrovascular events were examined by Cox regre ssion model. Analysis of 24-hour heart rate variability was performed in a subgroup of patients. Results: During 7.2 years, 8 patients, but no control subjects, had events (3 myocardial and 5 cerebral infarctions). Compared w ith Event(-) patients, Event(+) patients had: (1) orthostatic hypotension; (2) lower peak exercise heart rate; (3) lower plasma norepinephrine immedia tely after exercise; and (4) lower plasma epinephrine at peak exercise. Hig h frequency components in heart rate variability analysis were diminished i n Event(+) patients. Multivariate analysis-showed that peak heart rate (P = 0.04) and plasma epinephrine at peak exercise (P = 0.03) were independent predictors of subsequent events. Conclusions: These data suggest that chron otropic incompetence and lower plasma epinephrine response to exercise are associated with high risk of card iac-cerebrovascular events in patients wi th type 2 diabetes.