Figure 1. Metformin inhibited high glucose–induced vascular smooth muscle cell (VSMC) hyperplasia in a dose-dependent manner. (A) VSMC characterization by fluorescence microscopy. Expression of smooth muscle cell marker α-SMA was confirmed by red fluorescence. (B) CCK-8 evaluation of the effects of metformin on VSMC proliferation. Significant inhibition of high glucose–induced cell proliferation was found at metformin concentrations of 1, 5, and 10 mM. **p < 0.01 and ***p < 0.001 for between-group comparisons.