Acute cardiovascular effects of insulin in hyperglycaemic type I diabetics

Cardiovascular responses to high-dose (0.100 IE kg^-1 h^-1) and low-dose insulin infusion (0.005-0.01 IE kg^-1 h^-1) were examined in eight hyperglycaemic, resting type I diabetics. Mean blood glucose dropped from 15.9 to 7.1 mmol l^-1 and from 14.4 to 12.6 mmol l^-1, respectively, during 1 h. Blood pressure and heart rate did not change. There were no significant changes in absolute or relative left ventricular volumes, the 95% confidence interval (CI) for the difference between the doses in left ventricular ejection fraction was -6 to 8%. Calf blood volume increased on high-dose insulin (p = 0.05, CI for the difference over low-dose insulin 0.0 to 4.6 ml 100 ml^-1 tissue). Blood flow increased with 1.6 ml 100 ml^-1 tissue min^-1 with high-dose insulin and with 0.6 ml 100 ml^-1 tissue min^-1 with low-dose (CI for the difference -0.5 to 3.4). Noradrenaline increases were small and there was no difference between the doses (p = 0.47).