Flow of participants in randomised studies.

If this were the only trial available, it would be hard to recommend the interventions to delay the onset of diabetes in patients with IGT (although the intervention could be recommended for general health) owing to the methodological uncertainties. However, two subsequent, much larger and well-conducted studies have examined the combined effect of dietary and physical activity change. Both have documented the intervention that was achieved, and this provides a basis for identifying the level of change in diet and physical activity needed for effect. However, neither of these trials had separate arms examining the effect of diet alone or physical activity alone. As the relative effects of the two interventions are still unknown, patients should be advised to change both dietary and physical activity.