OBJECTIVES: Evaluate and compare clinical characteristics, risk factors, and disease severity (on angiographic findings) among diabetic and non-diabetic patients with coronary artery disease (CAD). METHODS: Observational study; consecutive patients admitted in ICU at tertiary care hospital, underwent coronary angiography (CAG) and diagnosed as CAD using standard definitions (acute coronary syndrome [ACS] i.e. myocardial infarction [MI], or unstable angina [UA]; or chronic stable angina [CSA]). The data included demographic information, risk factors for CAD, and angiographic findings. The linear stepwise regression was used to assess predictor of severity (more sever [double vessel disease, DVD or triple vessel disease, TVD] vs. less sever [minimal/non-critical disease or single vessel disease, SVD]) of CAD. The independent variables studied include age (<45 vs. ≥45 years), hypertension, diabetes, congestive heart failure (CHF, history of heart failure or ejection fraction [EF] ≤40%), gender, prior MI, final diagnosis, and MI type. RESULTS: Of 1166 consecutive patients, 1073 underwent CAG, considered eligible: normal coronaries, 113 (10.5%); leaving 960 patients with CAD (MI [289, 30.1%], UA [604, 62.9%], Undetermined ACS [32, 3.3%], CSA [35, 3.7%]); 30% patients were diabetic. Proportion of hypertensive patients was significantly higher among diabetics (57.7% vs. 34.9% non-diabetics, P<0.001). The presence of CHF in the diabetic as well as non-diabetic patients was similar. For all patients with CAD, around 40% had SVD on CAG; for diabetics, 35% patients had TVD whereas the proportion was only 24% among non-diabetics. In the linear stepwise regression, age ≥45 years, presence of CHF and diabetes showed significant positive correlation with the severity of CAD (p<0.05). CONCLUSIONS: Clustering of several cardiovascular risk factors at presentation may lead to the worse prognosis in patients with CAD from India. Findings from this study ascertain more severe angiographic findings in diabetic patients than that in non-diabetic controls regarding the severity of CAD.