Endocrine Abstracts

Background

Cardiac autonomic neuropathy (CAN) is a serious complication of diabetes mellitus (DM) that is strongly associated with increased risk of cardiovascular mortality. The significance of CAN has not been fully appreciated. Treatment of CAN includes physical activity.

Aim

To detect CAN status and measure the influence of physical activity on the autonomic nervous system using cardiovascular autonomic reflex tests (CARTs).

Methods

The study included 51 patients with type 2 diabetes: 30 were allocated to the control group (Con, n = 30) and the rest to the interval training (IT, n = 21) group. IT group exercised 3 times a week for 60 minutes for 4 month using a mobile device application. CAN was assessed on tilt table testing using 5 CARTs proposed by Ewing et al. (1985): parasympathetic function: heart rate (HR) response to the Valsalva manoeuvre (Valsalva ratio), HR response to deep breathing (E/I ratio) and HR response to standing (30 s/15 s ratio). Sympathetic function was measured by blood pressure (BP) responses to lying and standing as well as BP response to a sustained handgrip. Each test was assessed with a score of 0 for normal, 0.5 for borderline, and 1 for an abnormal result. Patients who had Ewing score ≥ 2 were classified as CAN positive.

Results

At baseline, CAN was detected in 33 (65%) patients. Ewing score in the CAN positive patients was 2.61 ± 0.74 and in CAN negative patients 1.08 ± 0.58. Probability of CAN before and after the intervention was 0.65 (95% CI - 0.38, 0.85) and 0.48 (0.22, 0.76) in the control group and 0.80 (0.48, 0.94) and 0.58 (0.27, 0.84) in the IT group. After the intervention between group (Con vs IT) change in CARTs and Ewing score was: Valsalva ratio 1.13 to 1.17 mm vs 1.12 to 1.25 mm (P-0.091); E/l ratio 12.85 to 12.51 mm vs 13.09 to 12.88 mm (p-0.902); 30s/15s ratio 1.04 to 1.06 mm vs 1.03 to 1.09 mm (p-0.233); BP response to lying and standing 8.69 to 9.45 mmHg vs 11.91 to 15.54 mmHg (P-0.420); BP response to handgrip 25.03 to 26.30 mmHg vs 26.76 to 22.70 mmHg (P-0.268); Ewing score 1.94 to 1.69 vs 2.04 to 1.74 (P-0.885).

Conclusions

CAN is a common complication of diabetes that often goes unrecognized. Physical activities can improve autonomic status.