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 α2 = 1.37 ± 0.21. This was significantly (P = 0.036) smaller than the reference “uncorrelated value” of α = 1.5, suggesting that glycemic fluctuation was negatively autocorrelated. In contrast, on a day with restricted NEAT in the long-range regime (>167.5 min), the exponent was α2 = 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.
1Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, JAPAN; 2Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi, JAPAN; 3Faculty of Health and Sports Science, Doshisha University, Kyoto, JAPAN; 4College of Engineering General Education, Nihon University, Fukushima, JAPAN; and 5Educational Physiology Laboratory, Graduate School of Education, The University of Tokyo, Tokyo, JAPAN
Address for correspondence: Yoshiharu Yamamoto, Ph.D., Graduate School of Education The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; E-mail: email@example.com.
Submitted for publication January 2012.
Accepted for publication July 2012.