insulintropin /in′səlintrop″in/ [L, insula, island] , a naturally occurring hormone produced in the intestines when food is ingested. It causes the release of insulin from the pancreas, which in turn regulates blood glucose levels. It has been administered to patients with type 2 diabetes but is not useful in its present form in the treatment of patients with type 1 diabetes, in whom the pancreas does not secrete insulin.