Fig. 2. Effects of metformin on the index of glucose tolerance and insulin resistance in KKAy mice. (A) Oral glucose tolerance test (OGTT); (B) fasting blood glucose (FBG); (C) serum insulin levels; (D) homeostasis model assessment of insulin resistance (HOMA-IR). Data shown in the bar graph are the mean ± SD; *p < 0.05, **p < 0.01 compared with control (n = 6–10/group).