Background: A major goal of diabetes care is the prevention of major cardiovascular events (CVE). Its success can be measured by quantifying trends over time in major CVE in adults with and without diabetes. Objective: To quantify trends in occurrence of major CVE in adults with and without diabetes who received care at 11 U.S. managed care organizations from 2005 to 2011. Methods: Study subjects included 2.4 million diabetes and non-diabetes subjects, frequency matched by age and gender (10,000,000 personyears). Clinical and demographic data were extracted from EMR at each site. Major CV events were identified based on primary discharge diagnoses from inpatient encounters for myocardial infarction/acute coronary syndrome (MI/ACS), stroke, and chronic heart failure (CHF). Age and sex-adjusted to the 2010 US census population even rates over time were computed. Generalized linear models were used to evaluate the significance of observed differences CVE trends in defined groups of subjects. Results: Mean age at cohort entry was 59 years (SD=14), 48% female, and 46% Whites. Rates per 1000 of CVE in 2010 for diabetes subjects were (MI/ACS: 4.4, stroke 4.0, CHF 6.9); event rates were more than twice the rate of non-diabetes subjects. A 5-year decline of 32% was observed in diabetes subjects and 27% in non-diabetes subjects for MI/ACS. Similar decline was observed by gender and age groups. Conclusions: Between 2005 and 2011, rates of major cardiovascular events (CVE) declined significantly among adults with diabetes. Decline was greater in patients with diabetes, likely associated with improvements in diabetes care.