Influence of aprotinin on insulin absorption and subcutaneous blood flow in type 1 (insulin-dependent) diabetes.

Ten normal-weight Type 1 (insulin-dependent) diabetic patients (12 h postprandial) with normal insulin requirement were given 125I-labelled soluble insulin (10 U) in the thigh together with aprotinin (10000 KIU) or its diluent on two consecutive mornings. Disappearance of 125I-radioactivity was followed continuously for 3 h by external detection and plasma free insulin measured by radioimmunoassay. Subcutaneous blood flow following aprotinin or diluent was studied concomitantly in the contralateral thigh by external monitoring of locally injected 133Xenon. Plasma free insulin increased significantly faster (p less than 0.05) and the insulin area under the curve was significantly (p less than 0.05) greater during the first hour after injection of insulin with aprotinin. Subcutaneous blood flow (rate constants for 133Xenon) was significantly higher with aprotinin (p less than 0.05), the highest flow occurring early after injection. In conclusion, subcutaneously injected soluble insulin is more rapidly absorbed by addition of aprotinin to the insulin solution in Type 1 diabetes. Blood flow increase at the injection site may explain part of this effect.