Resting ECG patterns were studied in 42 young diabetic patients and in 40 matched control subjects. There was no clinical ischemic heart disease in either group. Discriminant analysis showed significant differences between the two groups: diabetics typically had a higher heart rate, a leftward frontal QRS axis, a prolonged corrected QT interval and ST segment and T wave changes. Using resting ECG variables we were able to correctly classify 62 (75%) of the 82 patients studied. The findings support the existence of a nonischemic diabetic cardiopathy.