After a screening , diet/exercise run-in and drug wash-off period , a glimepiride + / - metformin dose titration/stabilization period and a 2-week , single-blind placebo run-in , 441 patients ( of ages 18-75 years ) were randomized to receive the addition of sitagliptin 100 mg once daily or placebo in a 1 : 1 ratio for 24 weeks .
