To examine left ventricular performance in diabetic patients without clinical evidence of cardiac involvement, systolic time intervals (pre-ejection period, left ventricular ejection time index and ratio of pre-ejection period to left ventricular ejection time) and echocardiographic measures (percentage changes in minor axis diameter, end-diastolic and end-systolic diameter, end- diastolic volume and end-systolic volumes, stroke volume and ejection fraction), were obtained. There were 89 diabetic patients and 93 control subjects evaluated for systolic time intervals, and 40 diabetic patients and 20 control subjects evaluated by echocardiogram. The diabetic group demonstrated significant (P less than 0.001) differences from the normal control group in each of the noninvasive measures of systolic time intervals. Pre-ejection period/left ventricular ejection time ration was increased by 25 percent and the pre-ejection period was increased by 12 percent in the diabetic patients. Among 40 diabetic patients studied by echocardiography, abnormal percentage change in minor axis diameter, (less than 30 percent) occurred in six individuals. Ejection fraction was decreased by 20 percent as compared to the control group, whereas end-diastolic pressure was not significantly different in the groups.