The effects of insulin on the cardiovascular system in patients with coronary heart disease.

In order to clarify the effects of insulin on the cardiovascular system in patients with and without coronary heart disease (CHD), we studied the changes of electrocardiogram (ECG), blood pressure, pulse rate, along with those of blood glucose, free fatty acid, immunoreactive insulin, cortisol and potassium during insulin tolerance test (ITT). The presence or absence of CHD was verified by the coronary angiography and various stress testings beforehand. In patients with CHD, ischemic ST-T wave changes were recorded following the increment of double product after insulin injection and these changes were quite similar to those recorded during exercise test. In patients without CHD, although hypoglycemia and suppression of lipolysis were achieved, ischemic ST-T wave changes were not recorded after insulin injection. Furthermore, in a patient with Triple Vessel Disease, ischemic changes of ECG provoked by ITT were abolished completely by the administration of nifedipine and propranolol. ITT may induce ischemic changes of ECG in patients with CHD by different mechanisms from those of exercise tests and it may provide a useful tool for the diagnosis of CHD in clinical applications.