A rapid review indicated higher recruitment rates in treatment trials than in prevention trials.

Objectives: To test the hypothesis that the percentage of patients screened that randomize differs between prevention and therapy trials.

Study Design And Setting: Rapid review of randomized controlled trials (RCTs) identified through published systematic reviews in August 2013. Individually randomized, parallel group controlled RCTs were eligible if they evaluated metformin monotherapy or exercise for the prevention or treatment of type 2 diabetes.