While SIRT1 is significantly associated with atherosclerosis and diabetic complications, its relevance to coronary lesions in patients with coronary artery disease and type 2 diabetes has not been specifically investigated. Thus, we assessed SIRT1 expression in peripheral blood mononuclear cells in these patients. We found that SIRT1 expression did not significantly correlate with syntax scores from coronary angiography (p > 0.05). Notably, plasma levels of the inflammatory cytokines tumor necrosis factor-α, monocyte chemoattractant protein-1, and high-sensitivity C-reactive protein were markedly higher in diabetic patients (p < 0.05). In addition, SIRT1 expression was negatively correlated with levels of these cytokines, as well as that of interleukin-6 (p < 0.05). In summary, the data indicate that SIRT1 expression in peripheral blood mononuclear cells is significantly correlated with inflammatory cytokines levels in patients with coronary artery disease and type 2 diabetes but not with the severity of coronary lesions.