Objectively measured light-intensity physical activity is independently associated with 2-H plasma glucose

<b>Objective</b>: We examined the associations of objectively measured sedentary time, light-intensity physical activity, and moderate- to vigorous-intensity activity with fasting and 2-h postchallenge plasma glucose in Australian adults. <br /><br /><b>Research Design and Methods</b>: A total of 67 men and 106 women (mean age ± SD 53.3 ± 11.9 years) without diagnosed diabetes were recruited from the 2004–2005 Australian Diabetes, Obesity, and Lifestyle (AusDiab) study. Physical activity was measured by Actigraph  accelerometers worn during waking hours for 7 consecutive days and summarized as sedentary time (accelerometer counts/min <100; average hours/day), light-intensity (counts/min 100-1951), and moderate- to vigorous-intensity (counts/min ≥1,952). An oral glucose tolerance test was used to ascertain 2-h plasma glucose and fasting plasma glucose. <br /><br /><b>Results</b>: After adjustment for confounders (including waist circumference), sedentary time was positively associated with 2-h plasma glucose (<i>b</i> = 0.29, 95% CI 0.11–0.48, <i>P</i> = 0.002); light-intensity activity time (<i>b</i> = –0.25, –0.45 to –0.06, <i>P </i>= 0.012) and moderate- to vigorous-intensity activity time (<i>b</i> = –1.07, –1.77 to –0.37, <i>P</i> = 0.003) were negatively associated. Light-intensity activity remained significantly associated with 2-h plasma glucose following further adjustment for moderate- to vigorous-intensity activity (<i>b</i> = –0.22, –0.42 to –0.03, <i>P </i>= 0.023). Associations of all activity measures with fasting plasma glucose were nonsignificant (<i>P</i> > 0.05). <b><br /><br />Conclusions</b>: These data provide the first objective evidence that light-intensity physical activity is beneficially associated with blood glucose and that sedentary time is unfavorably associated with blood glucose. These objective data support previous findings from studies using self-report measures, and suggest that substituting light-intensity activity for television viewing or other sedentary time may be a practical and achievable preventive strategy to reduce the risk of type 2 diabetes and cardiovascular disease.<br />