Introduction: Diabetes mellitus and new left bundle branch block (LBBB) increase the risk of adverse cardiac outcomes and are considered a coronary artery disease equivalent. We mean to investigate whether the presence of new or presumably new left bundle branch block could be the first manifestation of coronary artery disease (CAD) in diabetic patients. Methods: We performed a cross-sectional analysis to examine the association between new or presumably new left bundle branch block and extend of coronary artery disease, clinical risk factors, and echocardiographic fi ndings in diabetic and non-diabetic patients. The study included 273 patients with new LBBB admitted between January 2011 and June 2013 in the Cardiovascular Diseases Institute Iasi. The median follow up was 7 days (hospitalization period). Patients were divided into two groups according to their glycemic status: diabetic and non-diabetic patients. Results: Our study demonstrates that the presence of new LBBB in diabetic patients is unequivocally associated and could be the first manifestation of an extensive coronary artery disease. About 90% of all diabetic patients from our study were evaluated for the presence of coronary artery disease and we found that about half of them (48.09%) had either one, two or three significant vessel disease, as compared to non-diabetics, over two thirds of them having no vessel disease. History of hypertension, congestive heart failure, myocardial infarction and angina pectoris was significantly higher in diabetic as compared to non-diabetic controls, with statistically signifi cant diff erences (p < 0.001). Conclusions: In a clinical context, the new left bundle branch block suggests high coronary artery disease probability, especially in diabetic patients, and they should be evaluated through coronary angiography