Fig. 1: Metformin enhances blood glucose homeostasis by increasing glucotonic effect in the distal intestine and colon of C57BL/6 mice.

a IPGTT data for vehicle (saline)- and metformin-treated mice. Metformin-treated (MET) C57BL/6 mice (n = 4) exhibited better glucose tolerance than vehicle-treated (Veh) mice (n = 4, analysis of variance multiple t-test for multiple-comparison correction) and corresponding area under the curve (AUC). b Representative images of small-intestinal and colon ¹⁸F-FDG) autoradiography of metformin-treated and vehicle-treated mice after PBS lavage. Areas of higher FDG accumulation are red in color. c A graph showing the quantitative analysis of FDG uptake in the post-washing intestine tissue autography images. Metformin-treated limbs showed higher FDG uptake in the distal intestine, such as the ileum (IL) and colon (COL), compared with that in the corresponding vehicle-treated intestine, whereas no increase was observed in the proximal intestine, such as the duodenum (DUO) and jejunum (JEJU). d Colon PBS washing analysis. Colon PBS washings showed a larger amount of FDG excretion in the metformin-treated mice. All data are presented as the mean ± s.e.m. Data in a, c and d were analyzed using two-tailed Student’s t-tests; *P < 0.05, **P < 0.01, ***P < 0.001.