model of obese T2DM (20e24). Canagliflozin did not affect DPP4
activity, and teneligliptin did not inhibit SGLTs activity in vitro. In
addition, pharmacokinetic analysis revealed that there was no
drugedrug interaction between canagliflozin and teneligliptin.
Plasma DPP4 activity in ZDF rats was similarly inhibited by the
treatment with teneligliptin alone and with the combination of
these two drugs. Thus, the increase of glucose-induced plasma
aGLP-1 levels is likely to be due to enhanced secretion of GLP-1 by
canagliflozin and not potentiation of each mechanism.
SGLT1 plays a critical role in dietary glucose absorption in the
gastrointestinal tract, and acts as a glucose sensor for GLP-1
secretion from L cells (25,26). In contrast, SGLT1 inhibitors increase
plasma GLP-1 levels in diabetic rodents (27,28). Thus, the
role of SGLT1 in secreting GLP-1 is still controversial. We have
previously demonstrated the elevation of plasma aGLP-1 levels by
SGLT1 inhibition during OGTT in normal rodents (29). Clinical
studies in healthy subjects have also revealed delayed glucose
absorption and elevated plasma GLP-1 levels in a mixed-meal test
with canagliflozin, which inhibits SGLT1 activity at a concentration
approximately 150e160 times higher than that for SGLT2
(16). The intraluminal concentration of canagliflozin is likely to be
high enough to inhibit SGLT1 in the small intestines after oral
administration, whereas the plasma concentration of