The aim of this study was to assess the extent and the severity of coronary artery disease (CAD) in diabetic patients. Angiographic findings were retrospectively analysed in 50 diabetic and in 50 non-diabetic patients, matched for age and sex, undergoing coronary angiography for evaluation of clinically CAD or silent ischaemia. Baseline characteristics did not show any increase of cardiovascular risk in diabetics compared to the non-diabetic group. Diabetic patients present less chest pain and more electric abnormalities, reflecting CAD specificity for diabetic patients. Angiograms of the coronary tree were divided into 13 segments and two experienced angiographers have developed a methodic analysis of selected coronary segment stenosis. The number of significant coronary artery stenosis (> or = 50%) per patient was higher in diabetic than in non-diabetic subjects (5.06+/-2.16 vs 2.40+/-1.97, p < 0.05). Diabetics had also more left main CAD (7/50 vs 1/50,p < 0.05). Though we did not find at any time statistical difference for multivessel, distal or diffuse CAD between the two groups, nevertheless there are more diffuse and distal lesions of the diabetic coronary artery trees. This debate is not closed, there is always controversy concerning whether the angiographic findings in diabetic or non-diabetic patients are different. But these results corroborate the hypothesis of a greater severity of angiographic proven CAD in diabetic than in non-diabetic patients, especially in the left main coronary artery.