TNF and Impaired glucose tolerance: On the other hand, the DPS (Diabetes Prevention Study) [23] and several other trials have revealed that lifestyle changes can achieve both significant weight losses and improve glucose tolerance in middle-aged obese subjects with impaired glucose tolerance (IGT) [40,41,42] and that these are accompanied with an increase in the concentration of adiponectin and decrease in those of serum IL-6 and TNF-α [43,44,45].