OBJECTIVE: To evaluate chronic kidney disease (CKD) and cardiovascular outcomes in TECOS (Clinical trial reg. no. NCT00790205, clinicaltrials.gov) participants with type 2 diabetes and cardiovascular disease treated with sitagliptin, a dipeptidyl peptidase 4 inhibitor, according to baseline estimated glomerular filtration rate (eGFR). RESEARCH DESIGN AND METHODS: We used data from 14,671 TECOS participants assigned in a double-blind design to receive sitagliptin or placebo added to existing therapy, while aiming for glycemic equipoise between groups. Cardiovascular and CKD outcomes were evaluated over a median period of 3 years, with participants categorized at baseline into eGFR stages 1, 2, 3a, and 3b (≥90, 60-89, 45-59, or 30-44 mL/min/1.73 m, respectively). RESULTS: Participants with eGFR stage 3b were older, were more often female, and had a longer duration of diabetes. Four-point major adverse cardiovascular event rates increased with lower baseline eGFR (3.52, 3.55, 5.74, and 7.34 events/100 patient-years for stages 1-3b, respectively). Corresponding adjusted hazard ratios for stages 2, 3a, and 3b versus stage 1 were 0.93 (95% CI 0.82-1.06), 1.28 (1.10-1.49), and 1.39 (1.13-1.72), respectively. Sitagliptin therapy was not associated with cardiovascular outcomes for any eGFR stage (interaction P values were all >0.44). Kidney function declined at the same rate in both treatment groups, with a marginally lower but constant eGFR difference (-1.3 mL/min/1.73 m) in those participants who were assigned to sitagliptin. Treatment differences in these eGFR values remained after adjustment for region, baseline eGFR, baseline HbA, time of assessment, and within-study HbA levels. CONCLUSIONS: Impaired kidney function is associated with worse cardiovascular outcomes. Sitagliptin has no clinically significant impact on cardiovascular or CKD outcomes, irrespective of baseline eGFR.