Context: Accumulating evidences suggest that insulin like growth factor-1 (IGF-1) has protective vascular effects, supporting the possibility that IGF-1 deficiency may contribute to atherosclerosis. However, the relationship between plasma IGF-1 levels and endothelium-dependent vasodilatation is still unsettled.

Objective: We designed this present study to test the hypothesis that low plasma IGF-1 levels are associated with reduced endothelial function independently classical cardiovascular risk factors.

Setting: out-patients

Patients: One hundred never-treated hypertensive Caucasian subjects participating to the CAtanzaro MEtabolic RIsk factors Study (CATAMERIS) were recruited.

Interventions: Subjects underwent forearm blood flow (FBF) evaluation by strain-gauge plethysmography in response to increasing doses of acetylcholine (ACh) and sodium nitroprusside. Insulin sensitivity was estimated by the homeostasis model assessment (HOMA) index.

Results: Plasma IGF-1 levels were significantly correlated with age (r = -0.300; P = 0.001), HDL serum cholesterol (r = 0.211; P = 0.017), HOMA index (r = -0.355; P <0.0001), systolic blood pressure (r = -0.174; P = 0.042), glomerular filtration rate (GFR) (r = 0.228; P = 0.011) and ACh-stimulated FBF (r = 0.565; P <0.0001). In a stepwise forward multivariate regression analysis, the strongest predictor of ACh-stimulated FBF response were plasma IGF-1 levels accounting for 31.9% of its variation.

Conclusions: These results demonstrate, for the first time, that low plasma IGF-1 levels are highly associated with reduced endothelial function, an early step in atherogenesis process.