Background: Few studies have evaluated the effect of aerobic physical training on insulin sensitivity in subjects with type 2 diabetes treated with oral hypoglycemic agents. Most studies that involved nonobese subjects showed enhanced insulin sensitivity whereas studies involving obese subjects with type 2 diabetes are inconsistent because of concomitant fat loss.
Material/methods: Thirteen men with type 2 diabetes (6 nonobese and 7 obese) treated with oral hypoglycemic agents carried out a 12-week ergocycle program at 60% VO2 peak, one hour thrice a week. Diet and medications were maintained throughout the study. Insulin sensitivity was assessed with the euglycemic hyperinsulinemic clamp technique.
Results: VO2 peak (ml/kg/min) increased with exercise training. There were no significant changes in fat mass, percent body fat, fasting plasma glucose and insulin levels, glycated hemoglobin levels, or insulin sensitivity. However, when the subjects were separated into two groups, they showed different insulin sensitivity adaptation to training. In fact, nonobese subjects with type 2 diabetes showed an increase in insulin sensitivity, whereas no change was observed in the obese subjects.
Conclusions: These findings suggest that moderate aerobic exercise training of 3 months duration enhanced insulin sensitivity only in nonobese men with type 2 diabetes. Obese men with type 2 diabetes showed no benefit. Thus, adiposity per se may be a determining factor in the exercise-induced metabolic benefit of exercise training in subjects with type 2 diabetes.