Improving the Glycemic Regulation and the Psychoneuroimmunological Function by Enhancing the Vagal Tone in Prediabetes Individuals

Background. Compared to healthy population, individuals with prediabetes have a higher risk to develop diabetes and other cardiovascular diseases. However, these downward progressions might positively associate with autonomic nervous dysfunction, especially low vagal tone, which can be detected prior to comorbidities confirmed. The significant correlations among low autonomic nervous, high psychological distress, inflammatory status, and poor glycemic regulation, which are regarded as the psychoneuroimmunological integration, have not been well studied in prediabetes individuals. Heart rate variability (HRV) biofeedback is an easy and noninvasive intervention, which has been confirmed to strengthen baroreflex stimulation, facilitate the modulation of vagal tone, and further promote the physiological and psychological wellbeing in various diseases but not in prediabetes.

Objective. To test the effectiveness of HRV biofeedback on the modulating vagal tone and further enhancing the psychoneuroimmunological integration related to glycemic control, anti-inflammatory reaction, and psychological wellbeing.

Research methods. In this 2-year RCT study, the investigators are planning to recruit 90 prediabetes individuals and randomly assigned them into wait-list control group or experimental group by using the random sequence of numbers generated from the Excel Bernoulli Function. Experimental group will receive 8 once-a-week, individual, 30-min sessions of HRV biofeedback and 1 session of healthy lifestyle education. During the biofeedback training period, subjects will be encouraged to self- home practice of resonant frequency breathing for 20 mins, twice-a-day. Control group will receive 1 session of healthy lifestyle education. All subjects will be repeatedly assessed at time of enrollment, post-training (8 weeks after enrollment), 3-month, and 6-month follow-up. Repeated assessments will include physiological measurements of HRV, BDNF, GAS6, HbA1c, CRP, IL- 6, FPG, and salivary cortisol, and psychological measurements of perceived stress, anxiety, and depression.