CAG reduces plasma glucose in KM mice by inhibiting glucose uptake
To determine the glucose-decreasing effect of AST andCAG (Chemical structure were listed in Figure 1A), KM mice were administrated with AST and CAG for ten days. Metformin and Dapagliflozin were used as positive drugs, respectively. Compared with the vehicle group, metformin and Dapagliflozin efficiently decreased plasma glucose at each time point, and Dapagliflozin showed a higher efficacy. AST  could not show a significant effect on reducing plasma glucose, while CAG  showed a more substantial hypoglycemic effect and accompanied by a backward shift of the blood glucose absorption peak (Figure 1B), indicating that CAG could decrease glucose absorption in mice. The area under the curve of plasma glucose (AUC) further confirmed the glucose-decreasing effect of CAG  in mice, which was similar to metformin (Figure 1C).
There are two approaches for glucose-diminishing in mice, including promoting the glucose uptake and mobilization or inhibiting glucose absorption (Pandey et al., 2015). To reveal the underlying possible pattern of the glucose-decreasing inCAG -treated mice, we performed glucose uptake assay in cells by using the 2-(N -(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino)-2-deoxyglucose (2-NBDG) labelling method. Dapagliflozin markedly decreased glucose uptake by a decrease in the signal of the 2-NBDG within cells, and an opposite effect was observed in metformin-treated cells, which was in accordance with the previous studies (Lu et al., 2018). As shown in Figure 2, cells treated with CAG showed a similar pattern with that of Dapagliflozin, which was a significant reduction of the 2-NBDG signal. To be noted, metformin, Dapagliflozin, and CAG could all enhance insulin sensitivity as judged by an increase in the signal of the 2-NBDG in the combination group compared with groups in the absence of insulin. These results suggested that CAG , similar to Dapagliflozin, could inhibit glucose uptake.