Fig. 1

Metformin alleviates histologic changes and fibrosis in GK rat atrium. a Blood glucose levels during intraperitoneal glucose tolerance test in control and GK rats. b Hematoxylin–eosin staining of rat atrium (scale bar = 50 μm). c Masson’s staining of fibrotic tissues in the atrium (scale bar: 100 μm). The collagen fibers were stained blue. d Quantification of fibrotic areas as a percentage of total area (n = 6 per group). Normal distributed data were represented as mean ± SEM and non-normal distributed data were represented as median with interquartile range; * represents P < 0.05 vs Con; **represents P < 0.01 vs Con