A post hoc assessment of cardiovascular safety in 14,611 patients was performed by pooling data from 25 double-blind studies, which randomised patients at baseline to sitagliptin 100 mg/day or a non-sitagliptin comparator (i.e., non-exposed). Included studies were limited to those at least 12 weeks in duration (range: 12 to 104 weeks). Patient-level data were used in this analysis of major adverse cardiovascular events (MACE) including ischaemic events and cardiovascular deaths. Analyses were performed in three cohorts: the entire 25-study cohort, the cohort from placebo-controlled portions of studies (n=19), and the cohort from studies comparing sitagliptin to a sulphonylurea (n=3).In the entire cohort analysis, 78 patients had at least 1 reported MACE-related event, with 40 in the sitagliptin group and 38 in the non-exposed group. The exposure-adjusted incidence rate was 0.65 per 100 patient-years in the sitagliptin group and 0.74 in the non-exposed group (incidence rate ratio = 0.83 [95% confidence interval (CI): 0.53, 1.30]). In the analysis comparing sitagliptin to placebo, the exposure-adjusted incidence rate was 0.80 per 100-patient-years with sitagliptin and 0.76 with placebo (incidence rate ratio = 1.01 [95% CI: 0.55, 1.86]). In the analysis comparing sitagliptin to sulphonylurea, the exposure-adjusted incidence rate was 0.00 per 100 patient-years with sitagliptin and 0.86 with sulphonylurea (incidence rate ratio = 0.00 [95% CI: 0.00, 0.31]).A pooled analysis of 25 randomised clinical trials does not indicate that treatment with sitagliptin increases cardiovascular risk in patients with type 2 diabetes mellitus. In a subanalysis, a higher rate of cardiovascular-related events was associated with sulphonylurea relative to sitagliptin.