suMMARY Frequent abnormalities of left ventricular function were detected in 212 established diabetic patients using non-invasive techniques.Diabetics without angina or heart failure (n= 185) were significantly different from normal subjects (n=50) in beat-to-beat variation, ratio ofpre-ejection period to left ventricular ejection time, pre-ejection period index, isovolumic relaxation time, and interval from minimal dimension to mitral valve opening.Diabetics with angina (n=18) were similar to control subjects with angina (n=-25); they showed a significant dimension change during the isovolumic period as compared with other diabetics and normals. Sixteen diabetics without angina also showed outward motion during the isovolumic period (incoordinate relaxation) and 13 had abnormal systolic time intervals. Four diabetics suffered a myocardial infarction during the study period; all had previously shown incoordination.Comparison of diabetics with a diastolic blood pressure below 100 mmHg and between 100 and 125 mmHg showed that the latter had a thicker posterior wall; the enlarged systolic dimension and reduced fractional shortening were the result of the inclusion of five of the 11 diabetic subjects with heart failure in the hypertensive group. Insulin-dependent diabetics tend to have more pronounced abnormalities of left ventricular function than those not requiring insulin.Patients selected from a diabetic clinic frequently have impaired left ventricular function, and ventricular hypertrophy, when present, in primarily caused by hypertension.There is increasing evidence that diabetics have abnormalities of left ventricular function in the absence of clinical heart disease.'-6 Whether this results from small vessel disease of the myocardium, the metabolic effects of diabetes, or coronary artery disease is unknown, but the Framingham study' showed that diabetics suffered an incidence of heart failure in excess of that predicted from atherogenic risk factors.A wide range of abnormalities in systolic and diastolic left ventricular function has been shown in diabetics but the number of patients in each group tends to be small and usually only one clinical type is included. For example, patients without microvascular disease have been shown to have normal6 and abnormal' systolic time intervals, and those with