In whole, this study found that the mRNA and protein expressions of CTRP3 in visceral adipose tissue were progressively decreased at the pathogenic stages of insulin resistance and overt diabetes in a T2DM rats model induced by high-fat diet plus low-dose STZ intraperitoneal injection, while Ex-4, a GLP-1 receptor agonist, increased the expression of CTRP3 in such animals and improved their insulin sensitivity. This evidence concerns the gene GLP1R and diabetes mellitus.