Many chronic non-communicable diseases are at least partly caused by unhealthy lifestyles; an example is type 2 diabetes mellitus (T2DM). Lifestyle interventions have been shown to substantially reduce the risk of T2DM in high-risk patients. The risk reduction diminishes over time, but a long-term (> ten years) reduction is still achieved. Better compliance with the intervention and higher quality of lifestyle counselling during a longer period of time are predictors of improved long-term risk reduction. In patients with established T2DM, lifestyle intervention can be of great benefit as well. This can result in remission in a substantial proportion of the patients (12-46%) over a one-year period. A Mediterranean diet, which is low in both refined, starch-rich foods and high-sugar drinks, seems to result in the best outcomes. However, again the compliance and quality of lifestyle counselling are of crucial importance. Lifestyle medicine deserves serious attention in clinical practice.