In the last few decades, there has been a decrease in cardiovascular disease among patients with diabetes. In this retrospective cohort study, time trends in rates of cardiac event and disease management were compared between First Nations patients with diabetes versus others residing in Ontario, Canada. Patients with diabetes (20-105 years) between 1996 and 2015 were identified using linked health administrative databases. Outcomes included annual incidence of each hospitalization for myocardial infarction and heart failure, as well as mortality caused by ischemic heart disease. During the study, the rate of cardiac event incidence declined. Among First Nations men and women, the most significant relative annual declines were in ischemic heart disease death (4.4%; 95% confidence interval [CI], 3.0-5.9) and heart failure (5.4%; 95% CI, 4.5-6.4), respectively. When analyzing other patients, the most significant yearly declines in both men (6.3%, 95% CI, 6.1-6.5) and women (7.3%, 95% CI, 7.1-7.6) were ischemic heart disease death. The absolute rates of cardiac events were higher among First Nations patients than other patients. First Nations patients and other patients both demonstrated increases in prescriptions for cardioprotective medications, but First Nations patients also presented increased coronary artery revascularization procedures.