Daily Walking Combined With Diet Therapy Is a Useful Means for Obese NIDDM Patients Not Only to Reduce Body Weight But Also to Improve Insulin Sensitivity

OBJECTIVE: To evaluate the effects of walking combined with diet therapy (1,000-1,600 kcal/day) on insulin sensitivity in obese non-insulin-dependent diabetes mellitus (NIDDM) patients. RESEARCH DESIGN AND METHODS: Subjects were divided into two groups: 10 patients were managed by diet alone (group D), and 14 patients were placed in the diet and exercise group (group DE). Group DE was instructed to walk at least 10,000 steps/day on a flat field as monitored by pedometer (19,200 +/- 2,100 steps/day), and group D was told to maintain a normal daily routine (4,500 +/- 290 steps/day). A glucose clamp procedure at an insulin infusion rate of 40 microU.min-2.min-1 was performed before and after the 6- to 8-week training program. Mean serum insulin concentrations ranged from 720 to 790 pmol/l. RESULTS: While body weight (BW) in groups D and DE decreased significantly (P < 0.01) during the study, the amount of BW reduction in group DE was greater than that in group D (7.8 +/- 0.8 vs. 4.2 +/- 0.5 kg, P < 0.01). After training, glucose infusion rate (GIR) and metabolic clearance rate (MCR) in group D did not significantly increase; however, GIR and MCR increased significantly in group DE, from 17.21 +/- 1.11 to 26.09 +/- 1.11 mumol.kg-1.min-1 (P < 0.001) and from 3.0 +/- 0.3 to 5.3 +/- 0.4 ml.kg-1.min-1 (P < 0.001), respectively. The analysis of variance showed significant effects of exercise (time x exercise, P = 0.0005) for the improvement of MCR. Significant correlations were also observed between delta MCR and average steps per day (r = 0.7257, P < 0.005) in group DE. CONCLUSIONS: Walking, which can be safely performed and easily incorporated into daily life, can be recommended as an adjunct therapy to diet treatment in obese NIDDM patients, not only for BW reduction, but also for improvement of insulin sensitivity.