Blood Pressure Responses to Insulin

Kugelmann 1 reported 7 cases of angina pectoris who developed an elevation in blood pressure and substernal pain during hypoglycemia induced by the intravenous administration of insulin. The attacks of substernal pain and symptoms brought about by this procedure were similar to those which occurred spontaneously in these patients under ordinary circumstances. The studies of Kugelmann suggested to us using insulin hypoglycemia as a method of determining blood pressure responses. We have studied the blood pressure and blood sugar changes in normal individuals, in patients with essential hypertension, and in cases of Addison's disease following the intravenous administration of insulin. In each case a blood sugar determination (Folin Micro-method using venous blood) was made following a 12-hour fast; 15 units of insulin (Mulford) were then given intravenously, and subsequent blood sugar determinations made every 10 minutes for 90 minutes. To circumvent the effects due to emotional disturbances from repeated vena punctures only one puncture was made and the lumen of the needle kept unobstructed by a flow of 1 cc. normal saline per minute. Blood pressure readings with the patient supine and resting were made every 10 minutes for one-half hour preceding the test and every 2 minutes following the administration of insulin.

In 25 normal individuals following insulin and at a variable time interval, but usually within the first 40 minutes, there was a drop in blood sugar to an average level of 30 mg.% without any appreciable changes in blood pressure. There then occurred a sharp rise in blood pressure averaging 40 mm. Hg., systolic, and 7 mm. Hg., diastolic, over the previous readings. With this event the blood sugar rose from 30 mg.% to 46 mg.% with a gradual return to the fasting level. In the study of 20 cases of essential hypertension, the same phenomena occurred in a more striking fashion.