Inverse correlations between either plasma ADMA (A) or plasma SDMA (B) concentrations and NOx FSR, as well as between either plasma ADMA (C) or plasma SDMA (D) concentrations and the insulin sensitivity index (M). A two-order polynomial model was used for all the regression analysis and the linear fit. The multiple R2 regression values are reported. The R2 value of the correlation between age and NOx FSR (top-right panel) is slightly different from that calculated with a simple linear regression model (R2 = 0.23, P < 0.015). (The two highest SDMA values in the bottom-right panel belong to two diabetic subjects.) The P values for significance are also reported.