Diabetes mellitus (diabetes) is associated with significantly increased risk of peripheral vascular disease. Diabetes is classified as a coronary heart disease (CHD) risk equivalent, but it is unknown whether diabetes is a CHD risk equivalent for peripheral vascular disease. The objective was to evaluate the odds of peripheral arterial disease (PAD) or carotid artery stenosis (CAS) among participants with diabetes, CHD, or both, compared with participants without diabetes or CHD, in a nationwide vascular screening database. We hypothesized that diabetes and CHD would confer similar odds of PAD and CAS. A cross-sectional analysis of all eligible Life Line Screening Inc participants age 30 to 90 years with ankle brachial indices for PAD (ankle brachial index <0.9 in either leg) and carotid artery duplex ultrasonographic imaging for CAS (internal CAS ≥50%) was performed (N=3,522,890). Diabetes and CHD were present in 372,330 (10.7%) and 182,760 (5.8%) of participants, respectively; PAD and CAS were present in 155,000 (4.4%) and 130,347 (3.7%) of participants. After multivariable adjustment, PAD odds were 1.56 (95% CI 1.54-1.59) and 1.69 (95% CI 1.65-1.73) for participants with diabetes or CHD, respectively. Participants with both diabetes and CHD had 2.75-fold increased odds of PAD (95% CI 2.66-2.85). Findings were similar for CAS; compared with no diabetes or CHD, CAS odds increased for participants with diabetes alone (1.53, 95% CI 1.50-1.56), CHD alone (1.72, 95% CI 1.68-1.76), and both diabetes and CHD (2.57, 95% CI 2.49-2.66). Findings were consistent for women and men. In a large database of more than 3.5 million self-referred participants, diabetes was a CHD risk equivalent for PAD and CAS, and participants with comorbid diabetes and CHD had an especially robust association with PAD and CAS. Counseling regarding screening and prevention of peripheral vascular disease may be useful for patients with diabetes.