OBJECTIVES: To investigate the clinical effectiveness of increased physical activity within adults with type 2 diabetes. METHODS: A systematic review was undertaken to identify relevant randomized controlled trials (RCTs). MEDLINE, EMBASE and the Cochrane databases were searched for RCTs up to December 2010 as well as for systematic reviews to identify further RCTs. Reference lists were screened. For inclusion into the review, studies had to compare increased physical activity to no such an intervention with a follow-up period of at least 24 weeks. Patient-relevant outcomes were predefined: all-cause mortality, cardiovascular morbidity and mortality, health-related quality of life (HRQoL), end-stage renal disease, amputation, retinal damages, hypoglycemia and adverse events. The risk of bias of each individual study was assessed. RESULTS: Eight RCTs met the inclusion criteria and reported on predefined outcomes. The following interventions were compared to no such an intervention: endurance-training/strength-training or sessions with mixed (aerobic and resistance) training. The studies included 1202 patients with a mean age of 60 years. Only for the endpoints HRQoL and adverse events properly reported results were found: 4 studies analyzed HRQoL but all used different outcome measures, only one of the studies reported a statistically significant effect. 6 studies presented data on adverse events, 4 of them incompletely, 2 of them showing no significant treatment effect CONCLUSIONS: Although there is a vast body of literature on physical activity in adults with type 2 diabetes only 8 studies met the inclusion criteria. Evidence on patient-relevant endpoints was scarce, as most studies focused on HbA1c as their primary endpoint. We found no effect of increased physical activity on HRQoL and adverse events in patients with type 2 diabetes. Conclusions for other endpoints could not be drawn. Thus, there is a great demand for further studies with patient relevant primary endpoints.