Lack of Hypoglycemic Activity of Insulin after Intestinal Administration to the Rabbit

Abstract

The effect of insulin on blood glucose in the rabbit after direct instillation in the small intestine has been investigated. Crystalline Insulin, (U.S.P. U-40), administered via catheters placed in the duodenum, jejunum and ileum did not cause hypoglycemia at doses up to 50 U./kg. Tolbutamide (100 mg./kg.) produced a hypoglycemic response after oral and intestinal administration. The lack of response to insulin is believed to be due to the destruction of insulin by proteolytic enzymes of the gastrointestinal tract.