OBJECTIVE To examine the utility of repeated computed tomography (CT) coronary artery calcium (CAC) testing, we assessed risks of detectable CAC and its cardiovascular consequences in individuals with and without type 2 diabetes ages 45–85 years. RESEARCH DESIGN AND METHODS We included 5,836 individuals (618 with type 2 diabetes, 2,972 without baseline CAC) from the Multi-Ethnic Study of Atherosclerosis. With logistic and Cox regression we evaluated the impact of type 2 diabetes, diabetes treatment duration, and other predictors on prevalent and incident CAC. We used time-dependent Cox modeling of follow-up data (median 15.9 years) for two repeat CT exams and cardiovascular events to assess the association of CAC at follow-up CT with cardiovascular events. RESULTS For 45 year olds with type 2 diabetes, the likelihood of CAC at baseline was 23% vs. 17% for those without. Median age at incident CAC was 52.2 vs. 62.3 years for those with and without diabetes, respectively. Each 5 years of diabetes treatment increased the odds and hazard rate of CAC by 19% (95% CI 8–33) and 22% (95% CI 6–41). Male sex, White ethnicity/race, hypertension, hypercholesterolemia, obesity, and low serum creatinine also increased CAC. CAC at follow-up CT independently increased coronary heart disease rates. CONCLUSIONS We estimated cumulative CAC incidence to age 85 years. Patients with type 2 diabetes develop CAC at a younger age than those without diabetes. Because incident CAC is associated with increased coronary heart disease risk, the value of periodic CAC-based risk assessment in type 2 diabetes should be evaluated.