The vectorcardiographic (VCG) bites in diabetic patients were compared with those in nondiabetic control subjects using automated analysis of the conventional electrocardiogram (ECG). A 12-lead ECG was recorded from each of the 154 patients with non-insulin-dependent diabetes mellitus and 128 control subjects. The orthogonal leads X, Y, and Z were derived from the 12-lead ECG, from which a so-called 12-lead VCG was calculated for each of the 282 participants. A computer-based method for the detection and quantification of bites was applied to the 12-lead VCGs. Bite amplitudes in the horizontal loop had an average of 0.062 +/- 0.089 mV in the diabetic group, and 0.039 +/- 0.045 mV in the control group (P < .01). In the sagittal plane, the mean bite amplitude was also greater in the diabetic group than in the control group: 0.095 +/- 0.084 versus 0.069 +/- 0.058 mV, respectively (P < .01). A bite greater than 0.1 mV in the horizontal or sagittal planes was found in 56 diabetic patients (36%) and 27 control subjects (21%) with (P < .05) considered significant. In conclusion, the results of this study suggest that automated analysis of the 12-lead VCG can be valuable in diagnosing diabetic cardiomyopathy.