The effect of patterns and distributions of physical activity on blood glucose control in individuals with Type 2 Diabetes Mellitus: an exploratory study

Abstract

Physical activity (PA) is known to be beneficial for blood glucose control in individuals with Type 2 Diabetes Mellitus (T2DM). The American Diabetes Association (ADA) recommends 150 minutes or more of moderate to vigorous physical activity (MVPA) per week for individuals with T2DM, which may be perceived as an intimidating target. Recent evidence suggests that firstly, PA of all intensities, including lighter intensity activity, may be beneficial for blood glucose control and that secondly, the pattern in which PA is accumulated may be important, however this is poorly understood. The purpose of this thesis was to provide a detailed understanding of how the patterns (extent to which bouts of activity durations and intensities are accumulated within and between days) and distributions of all habitual PA (not just moderate and vigorous) influence daily glucose fluctations in individuals with T2DM. Free living PA was measured using an ActivPal accelerometer worn on the thigh and 24 hour glucose was measured using an iPro continuous glucose monitor in 33 participants (age, 72 ± 11 years). Stepping at a light-intensity and overall stepping time were associated with increased glucose time in target glucose range (TIR) and total daily area under the curve (AUC). Stepping at or above moderate intensity was associated with lower mean amplitude of glucose excursions (MAGE) (95% CI -0.016(-0.032, -0.001), p = 0.04). Individuals with high variation and high volumes of stepping time at or above moderate intensity and total daily steps were found to have significantly greater glucose TIR when compared to individuals with low variation and low volumes of activity. These findings suggest that daily light intensity activity is beneficial for daily glucose, and investigating activity on a daily basis rather than averaged over a week is crucial for improving the understanding of associations between glucose and activity in free-living.