OBJECTIVE: To examine physical activity (PA) thresholds affecting glucose, insulin and lipid concentrations and body fat composition in high-risk patients for type 2 diabetes (T2D). INTERVENTION: A total of 113 subjects of both genders having abnormal glucose levels in the oral glucose tolerance test were contacted. A total of 78 subjects with age 58.8 +/- 10.4 years and body mass index 31.7 +/- 5.3 kg/m2 were randomly assigned to intervention and control groups. Intervention consisted of a supervised walking (60 min three times weekly) for 3 months. All the subjects received standard care for PA and weight reduction and wore an accelerometer during the whole wakeful time. RESULTS: Over 80% of the daily steps clustered at an acceleration level of 0.3 to 0.7 g (2 to 3 km h -1 of walking) and were 5,870 in the intervention and 4,434 in the control group (p < 0.029). Between 0 and 3 months no significant changes were observed in fasting and 2-h glucose, body weight or maximal oxygen uptake. In contrast, changes in fasting and 2-h insulin (-3.4 mU/l, p = 0.035 and -26.6, p = 0.003, respectively), homeostasis model assessment-estimated insulin resistance (-1.0, p = 0.036), total cholesterol (-0.55 mmol/l, p = 0.041), low-density lipoprotein (LDL) cholesterol (-0.36 mmol/l, p = 0.008) and visceral fat area (-5.5 cm2, p = 0.030) were significantly greater in the intervention than in control subjects. The overall effects of PA were analyzed by quartiles of daily steps of all subjects. There were significant reductions in total and LDL cholesterol and visceral fat area between the highest (daily steps over 6,520) and the lowest quartile (1,780 to 2,810 daily steps). The changes associated with PA remained significant after adjustments of baseline, sex, age and body weight change. CONCLUSION: Habitual and structured PAs with the acceleration levels of 0.3 to 0.7 g and daily steps over 6,520, equivalent to walking at 2 to 3 km/h for 90 min daily, standing for the relative PA intensity of 30 to 35% of the maximal oxygen uptake, are clinically beneficial for overweight/obese and physically inactive individuals with a high risk for T2D.

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