Effect of Verapamil on Blood Glucose and Serum Insulin in Patients with Hyper‐ and Hypothyroidism

Publisher Website
Google Scholar
Abstract
Whether Ca antagonism may affect the basal peripheral venous insulin and/or glucose concentration in patients with abnormal thyroid function was studied. Verapamil, a Ca blocking agent, was infused i.v. over a period of 180 min into 5 thyrotoxic, 4 hypothyroid and for comparison 5 healthy controls. In the thyrotoxic group, verapamil induced a significant fall in glucose from 60 min on; it had no significant effect on the concomitant insulin concentration. After 4-9 mo., 4 of the 5 patients in this group were reinvestigated when euthyroid was due to antithyroid treatment. At that time verapamil was without effect on both insulin and glucose concentrations. In the hypothyroid patients, verapamil brought about a transient but significant increase in insulin. Accordingly, insulin increased by 93 .+-. 14% (P < 0.01) after 30 min. From 60 min on it had returned to the control level. The blood glucose concentration tended to fall in response to the infusion, but never reached significantly below the control level. When 3 of the 4 hypothyroid patients were reinvestigated in a euthyroid state after 2-4 mo. of oral thyroxine substitution, verapamil did not affect either the insulin or the glucose concentration. In the healthy subjects verapamil was without effect on both the insulin and glucose concentrations. An abnormal and different insulin-glucose response pattern to verapamil infusion in untreated hyper- and hypothyroid patients, which can be restored to normal by medical treatment, rendering these patients euthyroid was demonstrated.