The So-called Hyperglycemic Action of Insulin

Abstract

Collens and Murlin¹ have recently reported that the portal injection of insulin into dogs, in dosage of 0.05 to 0.1 unit per kilo weight, results in an immediate sharp rise of blood sugar of 20 to 80 mg. The rise occurs within 5 minutes and is then followed by a rapid decline. No such rise occurs following the systemic injection of the same dose of insulin. BÜBurger and Kramer 2 at about the same time reported that the injection of 10 to 20 units of insulin into the cubical vein of human beings produces a rise of blood sugar averaging 11.5%; intra jugular injection of 40 units into dogs of about 20 kilograms causes a rise averaging 28%; intraportal injection results in a rise averaging 46%. The rises occur within 5 minutes and are followed in 10 to 30 minutes by a rapid fall. In both of these reports, the results are interpreted as showing that insulin has a glycogenolytic action on the liver and that the hyperglycemia is a physiological or normal response to this action. Since such an action of insulin would have a bearing on work we were carrying out, we have gone into the matter in order to have a clearer understanding of its significance.

We have carried out experiments on dogs, corresponding to those described in the reports cited. We employed the Lilly insulin, as did Collens and Murlin, whereas the Burroughs Wellcome product was used by BÜBurger and Kramer. Using small doses, 0.1 unit per kilo, we obtained no rise in blood sugar on intrajugular injection, but a rise followed intraportal injection. Our maximum rise, however, was 15 mg. as compared to the 20 to 80 mg. rise of Collens and Murlin.