Physical activity and fasting glucose in adults with abnormal glucose metabolism: Findings from two independent cross-sectional studies in China

Background: Relationship between physical activity and fasting glucose in people with abnormal glucose metabolism is not well-known. This study was to investigate dose–response association between physical activity (PAT) and fasting glucose from two independent surveys among Chinese adults with abnormal glucose metabolism. Methods: 9419 adults with abnormal glucose metabolism from two independent surveys among Chinese adults were analyzed. Demographics, level of fasting glucose and PAT (in Met Score) were measured. Dose-response relationship between fasting glucose and PAT was assessed by natural cubic spline model. Certain threshold point was identified, and linear regression models were then used within each threshold interval to assess the liner relationship functions. Models were adjusted for confounding factors and were stratified in subgroup analyses by the main population characteristics including survey site, gender and age-group. Results: Overall the relationship between PAT and fasting glucose was not in a linear association (Linearity test: p < 0.0001). Level of fasting glucose was not associated with amount of PAT until a threshold point (square-rooted Met Score 66.6 (original Met score: 4436 MET-minutes per week), 95% confidence intervals (65.2–69.3 (4,251−4,802 MET-minutes per week)). After this threshold, an inverse association was observed: each increase of every standard deviation of square-rooted Met Score 29.8 (888 MET-minutes per week) was associated with a 0.25 mmol/L decrease in fasting glucose, with adjustment for confounding factors. The patterns of relationship were tested to be consistent in subgroup analyses by survey site, gender and age group. Conclusions: Our study indicated that among adults with abnormal glucose metabolism the level of fasting glucose was only inversely associated with square-rooted Met Score beyond a certain square-rooted Met Score amount.