Intravenous insulin has no effect on myocardial contractility or heart rate in healthy subjects.

To evaluate the acute effects of intravenous insulin on myocardial contractility and heart rate, echocardiography was performed in 12 healthy subjects and continuous heart rate recording in 11 healthy subjects before and during euglycaemic insulin and glucose infusion. The rate of insulin infusion was 0.5-1.0 mU X kg-1 X min-1. Serum insulin concentration was increased from 14.1 +/- 5.5 (mean +/- SD) to a plateau level of 91.3 +/- 22.8 mU/l. Left ventricular end-diastolic diameter, ejection phase indices and the heart rate remained at basal levels during the intervention. Thus moderate hyperinsulinaemia, induced by euglycaemic insulin and glucose infusion, has no inotropic or chronotropic effects in healthy supine subjects.