The Study on Lifestyle intervention and Impaired glucose tolerance Maastricht (SLIM), a randomized controlled trial, was designed to study the effect of a long-term combined diet-and-exercise intervention program on glucose tolerance in participants with impaired glucose tolerance (IGT). The SLIM lifestyle intervention (average follow-up 4.1 years) was effective to improve glucose tolerance and to prevent type 2 diabetes, but effects on cardio-metabolic risk factors, as clustered within the metabolic syndrome (MetS), remain unclear.