Cardiovascular effects of insulin: plasma volume changes in diabetics.

The mechanism by which insulin can alter the heart-rate and blood pressure of diabetics has been studied. Insulin decreased the plasma volume of 16 diabetics without complications by an average of 190 ml, a 6% change. Nine diabetics with severe autonomic neuropathy had no significant change in plasma volume after insulin. The basal plasma volume of autonomic neuropathy patients was smaller than that of the uncomplicated diabetics, perhaps accounting for the disparity observed between these two groups of diabetics. The decrease of plasma volume could thus account for the heart rate increase of uncomplicated diabetics, but not for the induction of hypotension in those with autonomic neuropathy.