The vascular responses attending major insulin hypoglycemic reactions in man have been reviewed by Kalinowsky and Hoch, Bellak, and others, but the special role of the capillary and other small vessels has received little attention. The importance of this role is implied in the investigations made on the influence of insulin in coma-provoking doses in regard to brain metabolism, the literature on which has been reviewed by Himwich, and since the capillary system is the final common path by which energy is transferred between blood elements and tissue cells.
This paper is concerned with the acute responses of the minute vasculature of two nondiabetic human subjects receiving massive doses of insulin five times weekly, over a three-month period. The more chronic vascular effects of this sequential experience of hypoglycemia are reported elsewhere.