Histological and morphometric changes of balloon injury-induced neointimal formation in insulin resistant rats. A) A representative of the uninjured carotid artery in normal control rats. B) A representative of histological change 4 week after balloon injury, showing neointimal hyperplasia in chow group treated with metformin. C) A representative of histological change of carotid artery 4 weeks after balloon injury, showing severe neointimal hyperplasia in rats with high fructose diet. D) A representative of histologic change 4 weeks after balloon injury in rats with high fructose diet and metformin administration (H&E staining, magnification x 100). Morphometric analyses on intimal area and intima to media ratio were performed to quantitate neointimal hyperplasia at week 1 (E and F) and week 4 (G and H). *P < 0.05 vs. Chow control, †P < 0.05 vs. Fructose group.