RELATIONSHIP BETWEEN INSULIN SENSITIVITY AND MAXIMAL FOREARM BLOOD-FLOW IN YOUNG MEN

Insulin resistance is a part of the metabolic cardiovascular syndrome. We aimed to test the hemodynamic hypothesis of insulin resistance, wh ich suggests that a decreased skeletal muscle blood supply with subseq uent reduced nutritional flow causes insulin resistance in skeletal mu scle. We assessed determinants of peripheral blood flow such as maxima l forearm blood flow (MFBF), minimal forearm vascular resistance (MFVR ), and whole blood viscosity (WBV) in 27 young men with borderline ele vation of blood pressure. Insulin sensitivity measured as glucose disp osal rate (GDR) correlated with MFBF (r=0.55, P=0.003), MFVR (r=-0.58, P=0.002), and WBV (r=-0.39, P=0.046 at shear rate 201 s(-1)). There w as no correlation between GDR and myocardial thickness or left ventric ular mass. In a stepwise multiple regression analysis, MFVR and WBV ex plained 54% of the variation in GDR. The relative increase in mean art erial blood pressure during a mental stress test, as a marker of react ivity or an alert reaction, was correlated with MFVR (r=0.56, P=0.002) and inversely with GDR (r=-0.45, P=0.018) and MFBF (r=-0.49, P=0.01) but not with cardiac dimensions. In a stepwise multiple regression ana lysis, 48% of the increase in blood pressure during a mental stress te st was explained by MFVR and WBV. Fasting insulin correlated with MFVR (r=0.41, P=0.036) and GDR (r=-0.62, P=0.001). These data show a posit ive association between the appearance of peripheral structural vascul ar changes as quantified through a hemodynamic technique and insulin r esistance in young men with borderline elevation of blood pressure. Th e cause-effect relationship of this finding needs further evaluations.