Microvascular complications and cardiac autonomic dysfunction in patients with diabetes mellitus type 1.

BACKGROUND The presence of cardiac autonomic neuropathy (CAN) in patients with diabetes mellitus (DM) is associated with increased mortality and chronic microvascular complications of diabetes. OBJECTIVE To investigate a possible association between specific findings of CAN during exercise testing (ET) and nephropathy and retinopathy in patients with type 1 DM. METHODS We conducted a cross-sectional study of 84 patients with type 1 DM. All patients underwent clinical laboratory evaluation and performed ET, and those who presented findings suggesting myocardial ischemia were excluded from data analysis (n = 3). The assessment of microvascular complications (retinopathy and nephropathy) was performed in the sample. RESULTS Patients with nephropathy and those with retinopathy achieved a lower heart rate (HR) at peak exercise (HR max) and smaller increase in HR in relation to rest (Peak ΔHR) compared with those without these complications. These patients also had a smaller reduction in HR in the second and 4(th) minutes after the end of the test (ΔHR recovery 2 and 4 minutes). After performing a multivariate analysis with control for possible confounding factors, the ΔHR recovery in two and four minutes, maximum HR and Peak ΔHR remained significantly associated with retinopathy; and ΔHR recovery in the second and 4(th) minutes remained associated with the presence of nephropathy. CONCLUSION The ET can be considered an additional tool for early detection of CAN and to identify patients at increased risk for microvascular complications of diabetes.