Background The risk of peripheral artery disease (PAD) in patients with diabetes mellitus (DM) and coronary artery disease (CAD) is an important and inadequately addressed issue. Our aim is to examine the impact of DM on risk of PAD in patients with different degrees of CAD characterized by coronary angiography (CAG). Methods Using nationwide registers we identified all patients aged >= 18 years, undergoing first time CAG between 2000 and 2012. Patients were categorized into DM/Non-DM group, and further classified into categories according to the degree of CAD i.e., no-vessel disease, single-vessel disease, double-vessel disease, triple-vessel disease, and diffuse disease. Risk of PAD was estimated by 5-year cumulative-incidence and adjusted multivariable Cox-regression models. Results We identified 116,491 patients undergoing first-time CAG. Among these, a total of 23.969 (20.58%) had DM. Cumulative-incidence of PAD among DM patients vs. non-DM were 8.8% vs. 4.9% for no-vessel disease, 8.2% vs. 4.8% for single-vessel disease, 10.2% vs. 6.0% for double-vessel disease, 13.0% vs. 8.4% for triple-vessel disease, and 6.8% vs. 6.1% for diffuse disease, respectively. For all patients with DM, the cox-regression analysis yielded significantly higher hazards of PAD compared with non-DM patients with HR 1.70 (no-vessel disease), 1.96 (single-vessel disease), 2.35 (double-vessel disease), 2.87 (triple-vessel disease), and 1.46 (diffuse disease), respectively (interaction-p 0.042). Conclusion DM appears to be associated with increased risk of PAD in patients with and without established CAD, with increasing risk in more extensive CAD. This observation indicates awareness on PAD risk in patients with DM, especially among patients with advanced CAD.