Diabetic Cardiovascular Autonomic Neuropathy Predicts Recurrent Cardiovascular Diseases in Patients with Type 2 Diabetes

Cardiovascular autonomic neuropathy (CAN) is a risk factor for cardiovascular disease (CVD) and mortality in patients with type 2 diabetes. This study evaluated the relationship between CAN and recurrent CVD in type 2 diabetes. A total of 206 patients with type 2 diabetes who had a history of CVD within 3 years of enrollment were consecutively recruited from January 2001 to December 2009 and followed-up until December 2015. Cardiovascular autonomic function tests were performed using the following heart rate variability parameters: expiration-to-inspiration ratio, response to Valsalva maneuver and standing. We estimated the recurrence of CVD events during the follow-up period. A total of 159 (77.2%) of the 206 patients enrolled completed the follow up, and 78 (49.1%) patients had recurrent episodes of CVD, with an incidence rate of 75.6 per 1,000 patient-years. The mean age and diabetes duration were 62.5 +/- 8.7 and 9.2 +/- 6.9 years, respectively. Patients who developed recurrent CVD also exhibited hypertension (P = 0.004), diabetic nephropathy (P = 0.012), higher mean systolic blood pressure (P = 0.006), urinary albumin excretion (P = 0.015), and mean triglyceride level (P = 0.035) than did patients without recurrent CVD. Multivariable Cox hazard regression analysis revealed that definite CAN was significantly associated with an increased risk of recurrent CVD (hazard ratio [HR] 3.03; 95% confidence interval [CI] 1.39-6.60; P = 0.005). Definite CAN was an independent predictor for recurrent CVD in patients with type 2 diabetes who had a known prior CVD event.