Background: The timing of enrolment following an acute coronary syndrome (ACS) may influence cardiovascular (CV) outcomes and potentially treatment effect in clinical trials. Understanding the timing and type of clinical events after an ACS will allow for clinicians to better tailor evidence-based treatments to optimize therapeutic effect. Using a large contemporary trial in patients with type 2 diabetes mellitus (T2DM) post-ACS, we examined the impact of timing of enrolment on subsequent CV outcomes. Methods: EXAMINE was a randomized trial of alogliptin versus placebo in 5,380 patients with T2DM and a recent ACS from October 2009 to March 2013. The primary outcome was a composite of CV death, nonfatal myocardial infarction (MI), or nonfatal stroke. The median follow-up was 18 months. In this post hoc analysis, we examined the occurrence of subsequent CV events by timing of enrollment divided by tertiles of time from ACS to randomization: 8-34, 35-56, and 57-141 days. Results: Patients randomized early (compared to the latest times) had less comorbidities at baseline including a history of heart failure (HF; 24.7% vs 33.0%), prior coronary artery bypass graft (9.6% vs 15.9%), or atrial fibrillation (5.9% vs 9.4%). Despite the reduced comorbidity burden, the risk of the primary outcome was highest in patients randomized early compared to the latest time (adjusted hazard ratio 1.47; 95% CI 1.21-1.74). Similarly, patients randomized early had an increased risk of recurrent MI (adjusted hazard ratio 1.51; 95% CI 1.17-1.96) and HF hospitalization (1.49; 95% CI 1.05-2.10). Conclusions: In a contemporary cohort of T2DM with a recent ACS, the risk for recurrent CV events including MI and HF hospitalization is elevated early after an ACS. Given the emergence of antihyperglycemic therapies that reduce the risk of MI and HF among patients with T2DM at high CV risk, future studies evaluating the initiation of these therapies in the early period following an ACS are warranted given the large burden of potentially modifiable CV events. Copyright © 2020 Elsevier Inc. All rights reserved.