Objective To observe colorectal tumor's growth in hyperglycemia mice and its vascular endothelial growth factor (VEGF)'s expression, insulin-like growth factor-1 (IGF-1)'s variation of blood through the experiment, then to ascertain whether type 2 diabetes mellitus (T2DM) danger factors to promote colorectal cancer happen and progress or not. Methods The mouse model of colorectal cancer combined T2DM was established. The volume of tumor was observed. After 5 weeks, all mice were executed and IGF-1 in the blood and the expression of VEGF in the tumor tissue was examined. Results The average tumor volume of colorectal tumor-diabetes group [(1628.5±882) mm3] were larger than that of colorectal tumor group [(1950.2±726) mm3] (P <0.05), and its expression IGF-1 of blood [(105.33±32.32) ng/ml] were higher than that of the control group [(69.83±25.57) ng/ml] and colorectal tumor group [(70.17±25.27) ng/ml] (P <0.05). The expression of VEGF [(70.0±11.5)%] in colorectal tumor-diabetes group were significantly higher than that of colorectal tumor group [(42.9±7.5)%] (P <0.05), too. Conclusion The model of T2DM and transplanted colorectal tumor can be duplicated successfully in ICR mice. Diabetes mellitus may be one reason of promoting colorectal cancer progress. Besides high blood glucose, its mechanism is the high level of IGF-1 which can inhibit apoptosis, promote cell differentiation and hyperplasia, and through inducing VEGF duplicating, heighten its expression, promote the tumor vessel growth, lead to tumor happen and metastasis.