Lack of Negative Correlation in Glucose Dynamics by Nonexercise Activity Thermogenesis Restriction in Healthy Adults

OGATA, H., K. NAKAMURA, M. SATO, K. TOKUYAMA, S. NAGASAKA, N. EBINE, K. KIYONO, and Y. YAMAMOTO. Lack of Negative Correlation in Glucose Dynamics by Nonexercise Activity Thermogenesis Restriction in Healthy Adults. Med. Sci. Sports Exerc., Vol. 45, No. 1, pp. 60-66, 2013. Introduction: Recently, nonexercise activity thermogenesis (NEAT) has been highlighted for its ability to prevent weight gain and obesity. It has also been shown that the long-range negative autocorrelation of glucose dynamics, considered to reflect long-term blood glucose controllability, breaks down in patients with diabetes. Purpose: The purpose of this study was to clarify the effect of restricted NEAT on the glycemic profile and/or control characterized by glucose autocorrelation. Methods: The glucose dynamics of 10 young healthy subjects were measured by continuous glucose monitoring during a day with normal activity and a day with restricted NEAT. To estimate the correlation property of the glycemic fluctuation, we used detrended fluctuation analysis, a method that analyzes the long-range temporal autocorrelation of signals. Results: In the long-range regime (>130 min) on a normal activity day, the detrended fluctuation analysis scaling exponent was alpha(2) = 1.37 +/- 0.21. This was significantly (P = 0.036) smaller than the reference "uncorrelated value" of alpha = 1.5, suggesting that glycemic fluctuation was negatively auto-correlated. In contrast, on a day with restricted NEAT in the long-range regime (>167.5 min), the exponent was alpha(2) = 1.57 +/- 0.15; this was significantly (P = 0.024) larger than 1.5, implying a lack of negative correlation. Conclusions: The negative autocorrelation of glucose dynamics disappears with restricted NEAT compared with normal activity. This indicates that NEAT, reflective of all nonvolitional muscle activity, plays an important role in long-range negative correlation and hence long-term blood glucose control in healthy young adults.