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

Background—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. Materials and methods—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. Results—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. Conclusion—Vascular insulin response is intact in non‐diabetic CAD patients in spite of insulin resistance and endothelial dysfunction.

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