Cardiac function was investigated by echocardiography in 24 short-term Type 1 diabetic patients with a mean diabetes duration of 7 years (range 4-14 years) during conditions of ordinary metabolic control. Compared to 24 age and sex matched normal control subjects, measurements of myocardial contractility as left ventricular fractional shortening and mean circumferential shortening velocity were increased by 12% and 20% respectively. Another 8 Type 1 diabetic patients were examined during conditions of poor (hyperglycaemia and ketosis) and good metabolic control. Following improved glycaemic control, left ventricular fractional shortening and mean circumferential shortening velocity decreased by 16% and 24% respectively. Our findings show that short-term Type 1 diabetes is associated with increased myocardial contractility. Furthermore, this condition is related to the state of metabolic control.