Studies of the characteristics of coronary artery disease (CAD) in diabetic patients have shown conflicting results. Only 2 studies exploring the severity of CAD, specifically in type 1 diabetes, have been published, and neither of them has used computer-aided quantitative coronary angiography, This retrospective study comprised 64 (24 women and 40 men) type 1 diabetic patients and nondiabetic control subjects. To estimate the severity, extent, and overall "atheroma burden" of CAD, we used quantitative coronary angiographic-based segmental analysis of coronary angiograms. Type 1 diabetic patients had greater global severity (p <0.001), global extent (p <0.001), and global atheroma burden (p <0.001) indexes than nondiabetic control subjects, Quantitative coronary angiographic-derived indexes of CAD were, on average, 1,4- to 4.3-fold higher in diabetic than in nondiabetic patients. These differences were particularly marked in women. We found that type 1 diabetic patients with a clinical indication for coronary angiography, especially women, have more severe, extensive, and distal type of CAD than individually matched nondiabetic control patients, Our findings, including a loss of sex difference for CAD among type 1 diabetic patients and a marked impact of type 1 diabetes in women, are not explained by established risk factors. (C) 2000 by Excerpta Medica, Inc.