Abstract

OBJECTIVE: We examined the associations of objectively-measured sedentary time, light-intensity physical activity, and moderate-to-vigorous intensity activity with fasting and 2-hr post-challenge plasma glucose in Australian adults.

RESEARCH DESIGN AND METHODS: 67 men and 106 women (mean age 53.3, SD 11.9 years) without diagnosed diabetes were recruited from the 2004-2005 AusDiab study. Physical activity was measured by Actigraph accelerometers worn during waking hours for seven consecutive days, and summarised as sedentary time (accelerometer counts/minute <100; average hours/day), light-intensity (counts/minute 100-1951), and moderate-to-vigorous intensity (counts/minute ≥1952). An oral glucose tolerance test was used to ascertain 2-hr plasma glucose and fasting plasma glucose.

RESULTS: After adjustment for confounders (including waist circumference), sedentary time was positively associated with 2-hr plasma glucose (b=0.29, 95% CI 0.11 to 0.48, p=0.002); light-intensity time (b=−0.25, −0.45 to −0.06, p=0.012) and moderate-to-vigorous intensity activity time (b=−1.07, −1.77 to −0.37, p=0.003) were negatively associated. Light intensity activity remained significantly associated with 2-hr plasma glucose following further adjustment for moderate-to-vigorous intensity activity (b=−0.22, −0.42 to −0.03, p=0.023). Associations of all activity measures with fasting plasma glucose were non-significant (p>0.05).

CONCLUSIONS: These data provide the first objective evidence that light-intensity physical activity is beneficially associated with blood glucose, and that sedentary time is unfavourably 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.