Decreased vagal activity and deviation in sympathetic activity precedes development of diabetes

<b>OBJECTIVE</b> <p>The objective of this study was to examine whether altered heart rate variability (HRV) could predict the risk of diabetes in Asians. </p> <p><b>RESEARCH DESIGN AND METHODS</b></p> <p>A cohort study was conducted in 54,075 adults without diabetes who underwent three-minute HRV measurement during health check-ups between 2011 and 2014 at Kangbuk Samsung Hospital. We analyzed the time domain [standard deviation of the normal-to-normal interval(SDNN) and root mean square difference(RMSSD)] and the frequency domain [total(TP), normalized low-frequency(LF), and normalized high-frequency(HF) power, and LF/HF ratio]. We compared the risk of diabetes until 2017 according to tertiles of heart rate and HRV variables, with tertile 1 serving as the reference group.</p> <p><b>RESULTS</b></p> <p>During 243,758.2 person-years, 1,369 subjects were diagnosed with diabetes. Both time and frequency domain variables were lower in the diabetes group, with the exception of those with normalized LF and LF/HF ratio. In Cox analysis, as SDNN, RMSSD, and normalized HF tertiles increased, the risk of diabetes decreased [hazard ratios (95% confidence intervals) of tertile 3: 0.81 (0.70-0.95), 0.76 (0.65-0.90) and 0.78 (0.67-0.91), respectively], whereas the risk of diabetes increased in the case of heart rate, normalized LF, and LF/HF ratio [hazard ratios (95% confidence intervals) of tertile 3: 1.41 (1.21-1.65), 1.32 (1.13-1.53), and 1.31 (1.13-1.53), respectively] after adjusting for age, sex, body mass index, smoking, drinking, systolic blood pressure, lipid level, c-reactive protein, and homeostasis model assessment of insulin resistance.</p> <p><b>CONCLUSIONS</b></p> <p>Abnormal HRV, especially decreased vagal activity and deviation in sympatho-vagal imbalance to sympathetic activity, might precede incident diabetes.</p>