Screening of Cardiovascular Autonomic Neuropathy in Patients with Diabetes by Quick and Simple Assessment of Sudomotor Function

Abstract

Aims: Cardiovascular Autonomic Neuropathy (CAN) is a common but overlooked complication of diabetes. Sympathetic C-fibers innervating sweat glands can be impaired early in patients with diabetes. SUDOSCAN, a new and non-invasive device that assesses sudomotor function, was compared to Heart Rate Variability (HRV) and to Ewing tests, known to be reliable methods for the investigation of CAN. Methods: 232 patients with diabetes were measured for HRV at rest and during moderate activity (stair climbing). Time and frequency domain analysis techniques, including measurement of Standard Deviation of the average NN intervals over 5 minutes (SDNN), High Frequency domain component (HF) and Low Frequency domain component (LF), were assessed during HRV testing. Heart rate variations during deep breathing and heart rate and blood pressure responses while standing, as described by Ewing were also assessed. Electrochemical Sweat Conductance (ESC) was measured on the hands and feet, and a risk score was calculated. Patients were classified according to their risk score. The classifications were as follow: no sweat dysfunction, moderate sweat dysfunction and high sweat dysfunction. All results are means ± SD. Results: The highest correlation was observed between the risk score based on sudomotor function and the LF component during moderate activity (r = 0.47, p 405 ms 2 (3 rd quartile) (46 ± 13 vs 30 ± 13, p < 0.001). When taking the LF power component during moderate activity < 90 ms 2 as a reference value, the AUC of the ROC curve for the SUDOSCAN risk score was 0.77. Conclusions: SUDOSCAN allowing quick and quantitative assessment of sudomotor function can be used for the early screening of cardiovascular autonomic neuropathy in daily clinical practice before more sophisticated, specific, and time-consuming tests.