The effects of telmisartan on insulin-resistant properties and expression of adiponectin receptors (AdipoRs) were investigated. A diabetic rat model was established using a high-fat diet and streptozotocin (25mg/kg) and primary rat coronary vascular smooth muscle cells (VSMCs) were used to elucidate the underlying mechanisms. The diabetic rats were insulin-resistant and exhibited weight gain, elevated blood pressures, and increased plasma triglyceride levels. These manifestations were ameliorated by elmisartan treatment. Four-week telmisartan therapy increased plasma adiponectin and decreased TNF-α expression in the coronary artery. Moreover, telmisartan significantly decreased AdipoR1 and AdipoR2 expression. Using high glucose-treated rat coronary VSMCs, telmisartan and PPAR-γ agonist GW1929 prominently stimulated PPAR-γ and decreased TNF-α expression. Interestingly, telmisartan or GW1929 also prevented hyperglycemia-induced downregulation of AdipoR1 and AdipoR2 expression. Additionally, GW9662 (PPAR-γ antagonist) significantly decreased the effects of telmisartan on AdipoR1 and AdipoR2 expression. These results demonstrated that telmisartan effectively ameliorated coronary insulin resistance and inflammation in diabetic rats and upregulated AdipoR1/R2 expression via activation of PPAR-γ in the coronary artery and VSMCs.