Vascular insulin response is preserved in non-diabetic patients with coronary artery disease, despite endothelial...

Patients with coronary artery disease (CAD) are often insulin resistant, a state that predisposes to increased atherosclerosis. Recently, it was suggested that a "vascular insulin resistance" could explain this association, causing endothelial dysfunction and hence atherosclerosis. We therefore studied the vascular insulin response in patients with CAD.

Nine non-diabetic patients with documented CAD and 31 lean healthy controls were examined. Forearm blood flow was measured by venous occlusion plethysmography. Dose-response studies of acetylcholine (ACh) and sodium nitroprusside (SNP) elicited endothelium-dependent and -independent vasodilation and were repeated during intra-arterial insulin infusion.

Patients were insulin resistant as determined by HOMA index. Insulin infusion resulted in high physiological levels of insulin in the forearm without systemic effects. Patients had a reduced ACh response but insulin infusion increased the ACh response equally in patients and controls (a mean increase of 74+/-37 vs 57+/-24%, patients vs controls, p=0.12). A minor increase of the SNP response was also noted during insulin infusion.

Vascular insulin response is intact in non-diabetic CAD patients in spite of insulin resistance and endothelial dysfunction.