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

AB 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 autocorrelated. 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