Improvement of oral glucose tolerance in the dog by feeding trypsin inhibitor. Role of the enteroinsular axis.

The influence of oral trypsin inhibitor (TI) or vehicle (V) during 4 weeks on oral glucose tolerance (OGT) and on the enteroinsular axis (EIA) of insulin, CCK, and gastrin was studied in five beagles. TI improved OGT throughout the 180-min test period. Incremental areas of insulin and gastrin did not differ from 0 to 60 min after TI and V treatment, but both increased significantly from 60 to 180 min after TI. From 0 to 60 min CCK decreased significantly in the TI group, whereas the differences (delta) in hormone changes (insulin, CCK, gastrin) observed during oral and intravenous glucose showed a decrease for their incremental areas during this period. During the 60- to 180-min period this hormone spectrum was reversed into a non-significant increase. We suggest that TI pretreatment improves oral glucose tolerance, possibly owing to decreased intestinal glucose absorption (early test period), augmentation of the incretin effect (later test period), or some unidentified factor.